Decades ago, every electronic device was sealed with one of two types of screws: a minus-shaped Flat/Slot head, or a plus-shaped Phillips head. There was no concept — at least, for common consumer electronics — that average people shouldn’t be able to unscrew their gadgets and take them apart. And the only reason to have multiple Flat or Phillips head screwdrivers was to handle bigger or smaller screws.

Times have changed, and “security screws” have become increasingly common. Apple actually started using tamper-resistant screws in its Macs years ago, but when it added Pentalobe screws to the iPhone 4, the media took notice, and there was a brief public flare-up (actual sample headline: “Apple iPhone 4 Uses ‘Evil,’ Tamper-Proof Screws”). Despite initial frustration, however, the solution turned out to be simple: buy an inexpensive Pentalobe screwdriver, or alternately, a multi-bit screwdriver with tons of different bits, like iFixit’s 54-Bit Driver Kit.

I’ve been using iFixit’s kit for so long and across so many great Mac upgrade projects that I consider it essential to my office; if a Mac, hard drive, or other peripheral needs to be opened, the 54-Bit Driver Kit almost always can do it. But since most people have no idea what Pentalobe, Torx, Tri-Wing, Hex and other bits look like or are supposed to do, I’ve assembled this guide to explain them all, focusing on the ones used in Apple products. By the time you’re done reading this article, you’ll have a good sense of the world of security screws, and the reasons it’s handy to keep a kit around to open anything up…

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A Brief Primer On Screw Drives (Yes, Drives)

As Wikipedia explains, a “screw drive” is the part of the screw driver that actually turns the screw, fitting into a groove on the screw’s head and allowing torque (turning power) to be applied to remove the screw. Virtually everyone knows the two most common types of screw drives: the centuries-old, minus-shaped “slot” or flat head, and the 80-year-old, plus-shaped Phillips (or more generally, cross-recess) head. But did you know that there are multiple sizes of these heads, as well as more than 10 different screw head shapes, ranging from stars to squares, triangles, and hexagons?

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Below, I list the type of screw drive in bold, as well as their most common sizes. Sizes are indicated with numbers, always with bigger numbers representing larger sizes, though the meaning of the numbers can be confusing. Some numbers represent millimeters (1.5, 2.5, 3.5) while others are just a sequence (1, 2, 3), and still others use obscure sequences (000, 00, 0, 1, 2). The smallest screw drives were historically used mostly by jewelers and watch shops, but as consumer electronics have shrunk — and, like the Apple Watch, become more jewelry-like — their screws have become similarly tiny.

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Using iFixit’s screw drive bits is simple: you just pull the bit out of the plastic organizing block it’s in, and pop it into a magnetic hexagonal hole atop a 3.75″ metal handle. iFixit also includes a nearly 2″-long metal extender, shown attached here, plus a flexible 5.5″ extender and 4mm to 1/4″ adapter. If you’ve ever tried to use a screwdriver in a very narrow hole, the value of the extenders will be instantly apparent; otherwise, the 3.75″ handle will be enough for most purposes.

Lots and Lots of Screws

The iFixit kit’s 54-piece set includes 9 blocks of 6 bits, which the company says were selected for the most commonly used screws in electronics. In my personal experience, only a handful of the bits get used over and over again, while others are used for one-off situations; paying $30 for the set gets you everything in advance, and saves you the $5 or $10 single screwdriver price you would otherwise buy on an as-needed basis (and wait around to have delivered). Note that there are a couple potentially useful bits that are notably absent from the set; I’ll highlight the missing ones below.

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Five of the six iFixit bits shown above are for Phillips head screws, one of the two most common types of screws in existence. They are shaped like plus symbols, except for a tiny central bulge designed to reduce the likelihood of stripping (damaging/rendering inaccessible) screws. iFixit’s set includes jeweler-caliber tiny PH000 and PH00 tips, which are ultra-sharp, plus larger and more common PH0, PH1, and PH2 tips; one of these is typically all that’s needed to swap RAM in a Mac. (The set does not include super-small PH0000 or bigger, widely available PH3 and PH4 sizes.) On the far right is a single Triangle bit (3mm), which isn’t used for any Apple products, and not to be confused with the Tri-Wing discussed later. Triangle bits are sometimes used in toys.

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The next collection of screw drives is the Slot or Flatheads, which are shown above in 1mm, 1.3mm, 1.5mm, 2mm, 2.5mm, and 3mm versions. While the 2mm version is used for many Mac screws, this collection of minus-shaped bits can be used to remove some of the most common small and large screws in other products; the smallest ones can also be used to fix some glasses and watches. In a pinch, Flatheads can sometimes be used to extricate a cross/Phillips screw that has been stripped.

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Following the 3.5mm and 4mm Flatheads are a set of JIS (Japanese Industrial Standard) bits, a cross-shaped Phillips head alternative used in Japanese-made products. The J000, J00, J0, and J1 bits parallel the small- to medium-sized PH000, PH00, PH0 and PH1, but the tip shape is very subtly different. If you see a really small plus-shaped screw in your Apple product, it’s more likely to be a JIS than a Phillips head.

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This is a collection of Torx screw bits, sometimes (confusingly) known as star screws or 6lobe screws; their distinctive shape makes them tough to remove unless you have the right type and size of bit. The smallest Torx bits look like six-pointed stars, while the larger sizes add a circular post to the center for security reasons. Torx T5, T6 and T8 bits can be used to disassemble many Macs.

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These Tamper-Resistant Torx (or Torx TR) bits prevent Flatheads from being inserted, which would defeat the security. The bits labeled T7 through T20 in iFixit’s set are tamper-resistant.

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On the right of the Torx T9 to T20 bits are two Tri-wing bits labelled Y0 and Y1. Unlike the Triangle bit in the first bit picture above, the Tri-wing bits have three blades rather than a large triangular block, so they look like Phillips heads from certain angles, but only fit into Y-shaped screws. Apple notably uses Tri-wing screws to secure the S1 processor inside the Apple Watch, but they’re even smaller than the Y0 here; you’ll need a precision Tri-wing set like this one to get the Apple Watch’s screws out. Larger Tri-wings have been found in certain MacBooks, as well.

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On the right of this set are three Square bits, which look like their name suggests, and were used more often a long time ago; they are not used in Apple products. The Pentalobe bits on the left of this block are “star” bits like the small six-point Torx stars, but with only five points. Apple notably uses Pentalobe screws in Macs and iPhones, though the ones in the iFixit kit are notably Mac-sized; even the smallest (2) version is too large for the two screws found on the bottoms of all iPhones since the iPhone 4. It’s possible that the Pentalobe 2 in my set has dulled over time, but even though it’s billed by iFixit as right-sized for iPhones, it’s too big for those screws.

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To remove the Pentalobe screws from an iPhone, you’ll need a P1-sized tip like the Wiha Precision Driver P1. iFixit has for years recommended that users who remove those tiny Pentalobes replace them with regular ones instead, selling a “Liberation Kit” including a P1 driver and two replacement screws. Unless you really plan to open and close your iPhone with frequency, that’s not necessary, but it’s up to you.

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The iFixit set includes six separate Hex or Allen bits, starting with the microscopic 0.7mm H0.7 and ending with the 6mm H6.0. While there are numerous standalone Allen/Hex wrench sets out there, very few of them have the ultra-small H0.7 and H0.9 or small H1.3 and H1.5 sizes; they typically begin with 2mm wrenches and move up from there. Older Mac keyboards were secured by a mix of Torx and 1.3mm Hex screws, just as one example of how one of these bits could prove useful.

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Even if you don’t find a Hex screw in your Mac or peripheral, they’re useful for other things. I’ve most often found them handy for tightening furniture, such as the desk my Mac sits on, or Hex screws on monitor/tablet-supporting stands. These turn out to be relatively common screws for certain types of products.

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Last and also least in this collection are the six Nut Drivers, ranging from 2.5mm to 5mm in size. These large bits are effectively the inverse of the Hex/Allen bits, and designed to handle screws that look like protruding hexagonal bolts — think Frankenstein’s neck. I don’t really see these on electronics products these days; they’re far more common in furniture, though not particularly common these days, especially in these sizes.

Depending on how bit-obsessed you want to be, there are even more elaborate sets out there, such as Tekton’s $36 135-piece set with a ratcheting screwdriver, Anytime’s $27 101-piece set focused on security screws, and $16 to $27 Delcast kits with Pentalobes and other tools. The $30 iFixit 54 Bit Driver Kit is in the middle of the pack price-wise, but focuses pretty well on the needs of Mac owners. Go with something more extensive if your repair needs go beyond the Mac, or with a simpler Pentalobe-focused set if you’re only interested in opening iPhones.

More Information

If you’d like to learn about some of the more obscure security screws out there, such as the Spanner head/Snake-eye, Bristol, or Double-square, this Wikipedia entry is packed with information.

Additionally, I’ve covered a lot of other Mac-related upgrade topics that benefit from understanding the security screws discussed above. Check out a full list of my 9to5Mac guides, editorials, and reviews; if you click on Older Posts at the bottom of the page, you can see everything!

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