Re-arrange your modules in seconds! These things are great, they can be securely tightened with regular finger tightening without using any tool. They can also be tightened with a regular screwdriver.
M3 Knurlies are black, M2.5 are silver – both come with the washer already on the screw. Check your rails before selecting which size.
These are 6.5mm long from the base of the head to the end of the screw. The washer is 0.5mm long making usable length 6mm.