M6 threads are 6mm metric screws. The standard metric rack screw is called M6 x 1. The ‘M’ means it’s metric. The ‘6’ is the outside diameter measured in millimeters, and the ‘1’ is the distance between adjacent threads, also in millimeters.

Does M6 mean 6mm?

M6 refers to a metric 6 mm screw. The outside diameter of the threads is 6 mm. The standard metric rack screw is actually an M6 x 0.1 mm. The number 0.1 mm refers to 0.1 threads per millimeter.

Will a M6 bolt fit in a 6mm hole?

Since they are bolt-nut pairs, you may be able to substitute 6mm, but the 1-1/4″ length will still be essential.