i think most people are going with seirra precision, or unitracts, i don't know if the
top flight giant corsair robarts will work , also ck out spring air. I tried to find a web site for sierra, but couldn't. Unitracts is a UK company, its www.unitracts.com.uk . SPring Air, is www.retracts.com, their phone is 321-728-9002 , in fLORIDA.

good luck