I have a set of jewel screwdriver bits, for torx, Phillips, etc. However, there's one bit that looks like a Phillips head that's inverted or backwards, and I can't figure out its function.

The bit is a female Phillips head, and the label in the kit just says "PH 2", which I imagine means Phillips head, size 2.

What do you use this for? Getting another screwdriver out of something?

Inverted phillips screwdriver bit

Edit: Here's most of the set, in case it helps. The top left bit (not in the handle) is the one I'm talking about. The set is filled with various bits that you would use on small screws.

whole set

Here's the web archive for the amazon product. I bought it in the U.S., whose page has been removed, but the same product is on the U.K. page. According to the product details, the screw bit is a Cross size: PH2. Maybe it was simply a miscommunication with the manufacturer when the bits were milled?

  • If the other end is the tool, e. g. Allen wrench, then perhaps it's to be used with a Phillips-head driver? Or is it a magnet, to make a screwdriver a pick-up tool?? Jul 13, 2018 at 22:32
  • The other end is the same hex size that all the other 50+ bits are, designed to fit the jewel screwdriver shaft. It isn't magnetic, either.
    – Stephen S
    Jul 13, 2018 at 22:34
  • @StephenSchrauger "same hex size that all the other 50+ bits," What other 50+ bits ? we do not know what you are talking about unless you give specifics and we can NOT see the other hex size of the 50+ bits.
    – Alaska Man
    Jul 14, 2018 at 0:31
  • @Alaskaman I have a set of jewel bits. Various phillips, torx, and other bits. This is one of the bits. Does the hex size matter at all? That's just the portion that every bit has (ex one part of a torx bit is the torx, and the other end is the hex, which plugs into the screwdriver handle). Edit: I added a photo of the set.
    – Stephen S
    Jul 14, 2018 at 1:25
  • The bits at rhe left end of each row look different from all the others, but similar to each other. (Different color, knurled barrel). What are those other bits from the left side?
    – Mark
    Jul 14, 2018 at 2:03

2 Answers 2


The bit that you are asking about is what is called a "concave Phillips" or "inverted Phillips" bit. They are used for removing screws that look like this:

enter image description here

(picture found at ebuy7.com)

The cross pattern on the screw head is actually raised.

  • I realize it's been half a decade since you wrote your answer, but in what situations are these screws typically used? Would it be better to ask as a separate question on this SE, or would it be off-topic? Nov 3, 2023 at 9:29
  • I have no idea of the general use for this type of screw. It is possible to realize that a normal Philips type screw head actually can weaken the head of a screw since the slot displaces some of the head material. If forming the head so that the feature "sticks out" instead there is more head material and thus may be stronger. Probably especially applicable for low quality screws made of soft metal.
    – Michael Karas
    Dec 2, 2023 at 19:48
  • Thank you for your thoughts on it. That seems like a reasonable possibility. Another possibility, perhaps, is "pseudo-security", as most people probably don't have a screwdriver that matches the head. Dec 3, 2023 at 17:08

maybe used for a specific size thumb screw
enter image description here

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