Abstract: A reamer held in its required non-rotative condition for effective reaming by a rearwardly disposed key and key way construction, and wherein an elastomeric ring in encircling relation about the reamer maintains, without adverse effect on the holding function of the key and key way, the key in a clearance position within its cooperating key way, to thereby permit adjusting movements in the reamer to correct for misalignment between the reamer and the drilled hole to be reamed.