Model A Locking Caps
This is the cap only. The 1928-29 is threaded, and the 1930-31 has tabs. Both lock in place with allen screws so they can't be removed without tools. See instructions below for 1930-31 with reproduction radiators. Top part of cap that flips open is drilled to accept the A-18354-CR or -WR moto meters. U.S.A.