If you have a M37 you know what this is. Main spring rod unique to the m37 only. These do wear out and are extremely hard to find I had a M37 premay and sold a few years back just found this in the parts drawer. This one is NOS stock and unused
$125 plus shipping
John Ciszek
07SOT
+1.510.406.4193
jecayc@hotmail.com