WLFuller loves to confuse. They have an online catalogue, but C10M isn't there. It appears to be the same countersink/drill as "C10". The cone drill has a diameter of 13/64" and the outer diameter of the countersink is 7/16". The reason these numbers are important is because "#10 screw" defines the diameter of the screw, but does not determine the size of the countersink or drill bit. WLFuller has several recommended options for Prop #10. The head hole can be 7/16 or 1/2 and the drill bitโฆ