Hex-nuts M4 10pc

 boostoman 315 points

they should be ok

 Videomaker 1 points

There are different size shafts,so it will depend on what size you have. If you can't find the info from the motor supplier, you could use a micrometer to measure it.

 fireball412 414 points

M4 usually has a 3.2mm center bore hole

 ModHeic 37 points

It should be 3.3 mm ...

 gas wolf 51 points

M4 indicate the type of screw. Is metric type (M) with nominal diameter of 4 mm.

 Napstr 692 points

These are designed to screw onto a 4mm thread so the inside diameter would be 3.5mm

 Greg 12 points

they fit m4 sized bolts

 Colt1873 166 points

4mm nominal for the actual major and minor diameter you need the class of fit