This Winchester manufactured early variation action slide lock with both springs is for the earlier model 12 slide action shotgun in 12 gauge and is in very good condition with light wear. The early variation action slide lock has a checkered button where as the late variation has a serrated button.  (file photo)

Note: Winchester model 12 slide action shotguns with the following gauges and serial numbers have been observed with this part:

12 Gauge: 318823 & 588236