a photo of the bolt in question

A previous owner fitted the light fitting pictured above, and has not left me a tool to remove the bolt. The bulb has blown so I need to get in to the unit. The head diameter is about 12mm and the gap between the two notches is about 6mm. I would like to remove it with some technique involving more finesse than simply smashing up the fitting and/or drilling out the bolt.

I hope someone can recognise the bolt and give me a search term which will let me cheaply buy a bit for this bolt from somewhere like Ebay UK.

6 Answers 6


It's called a spanner slotted (or slotted spanner) head. Useful site here. Hard to find in the UK, why the owner used one I cannot imagine. Screwfix doesn't have them. This site may do, although it is international. You'll need to figure out the correct size before you order.

Alternatively get a real cheap flat-head screwdriver the right width and file down the middle until you get the right notch.

If you can grip it with a pliers try a pair of locking pliers and unscrewing it that way I keep a mini vise-grips handy for that sort of thing.

  • 12
    I usually bend a paperclip into a u shape, stick the two ends into the screw slots, then get a set of pliers and grab the paperclip right at the screw face... then turn.
    – Hightower
    Commented Oct 9, 2012 at 9:14
  • 1
    Could work, depends on how tight it has been screwed in.
    – GdD
    Commented Oct 9, 2012 at 10:24
  • 2
    You can also gang two thin screwdrivers together by clamping them between a pair of pieces of wood (to keep the alignment). If it's really stubborn, cut grooves in the wood so the screwdrivers don't spill. Commented Oct 9, 2012 at 12:59
  • 4
    If you run into these with any regularity, you can find "security bit sets" online for ten's of dollars, which typically contain several sizes of spanner bits in addition to many others. Handy to have for those off times you run into these.
    – gregmac
    Commented Mar 6, 2014 at 22:47
  • 3
    Alternate solution would be to use a cutting disk with a rotary tool to carve out a straight slot between the notches in the screw head. Then you could just use a normal screwdriver to open the fitting, and you wouldn't have to go searching for your custom tool the next time the bulb burns out. Commented Nov 11, 2015 at 16:05

I think that's a Spanner bit:

Four piece set


Find a pair of scissors with a not-so-flimsy build, open them to the correct angle and insert the points into the two slots. If the screw is not too tight, this may work.


Variously known as a spanner-head, snake-eye or pig-nose screwdriver. I had exactly the same problem as the OP - I think I have the same light fixing. Presumably the idea of using a weird fixing is to protect from vandalism, but it's a right pain if you don't pass on the right tool to subsequent owners.

I put off replacing a blown bulb for months, looked all over for the right tool but couldn't find one. I was just about to start grinding a hole in an old screwdriver when I tried undoing it by hand, and found that it was only on finger-tight. So to anyone facing the same problem - try unscrewing it by hand!!!

Otherwise I suspect it's cheaper to smash up the fixing and buy a new fixing, than it is to order a special screwdriver from overseas.


I took a simple screwdriver (AC tester actually) and cut the middle of it with a rotary grinder. It works for me to open these screws whenever I barge into them once in a few years. No need to search for rare bits for this one.


I had one of these with a 12mm diameter head and about 6mm between the pins. Couldn't find the correct spanner / snake eye bit at all.

I brought a 10mm screwdriver and used a 6mm stone grinding bit in a dremel to shape it correctly. Took about 10 mins and worked great.

Suffice to say I replaced the weird security screws with normal ones after!

  • 2
    This is exactly what the second paragraph of GdD's answer said. If you'd care to expand on this to offer something new...
    – FreeMan
    Commented Feb 22, 2022 at 12:54
  • It's also exactly what the complete answer from deE is.
    – MarkL
    Commented Feb 22, 2022 at 18:27

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