What size are replacement screws on the I2C case

What size are the I2C encoder screws that go on the back of a 393 motor? I tired a search and could not find it but I could have sworn I have seen this answered before.

I found from the motor page, the normal case screws are M2x0.6x10mm Self Tapping but I can not find the size of the screws listed for the encoder screws on the I2C sensors.

I assume they are also M2 but it appears to be 18mm long by my ruler (is it measured from the bottom of the head to the end or do you include the screw head too?)

I have tried the #1 phillips, the small flathead, the snips clamped down like a vice but these things just want to strip themselves like crazy! I am ready to snip them off and get a new set (hence the question).