Looks like a Clarkson autolock collet
From what i remember using mine i think just a normal RH Mate...Very rarely use my head as just use the set of R8,s i have straight up the snoutAre those not LH thread?
looks close... will check tomorow.....Might be a 4c collet also the size looks about right.
Hope i am not going mad here with confusion
Nope! i am going to embrace my madness with pride mate as i did think they where Clarkson looked at my Clarkson chuck today and hit myself on the hand with a nice old heavy fileI think the only confusion is that you (and I) might have meant Crawford Trugrip collets.