The unthreaded tremolo arm fits into a hard plastic sleeve staying where you put it, via a small set screw on the side of the bridge that faces the tail end of the guitar therefore it will not wobble or break off in the block. Fits all US-made PRS tremolo models, plus it is made of stainless steel.
CALIFORNIA PROPOSITION 65 WARNING

WARNING: Cancer and Reproductive Harm -
www.P65Warnings.ca.gov.