This Colt manufactured brass magazine feed throat with tube extension is for the small frame Lightning slide action rimfire rifle and is in very good condition with a light tarnish to the brass and a brownish gray patina with rust specks on the tube extension. (file photo)

Note: Colt small frame Lightning slide action rimfire rifles with the following serial numbers have been observed with this part: 11739, 35792, 37115 & 81614