Nickel Rivets for many popular plastics backed with small keeper washers. These can be used for Seeburg selection playing when the backing metal is missing. With backing metal a slightly longer rivet is required. 15 pieces.
Traditionally these are formed over by using a tool called a “hand rivet squeezer”. Most people wont have one of these handy. The best way to form the back over is to insert the rivet in the from side, and use a solid piece of steel and a ball peen hammer. Press the stack down, include any backup plates of metal or washers, and carefully tap the tubular side of the rivet to mushroom it over. For best results keeping the face, plastic, backup, as tight as possible and solid square centered taps. IF you tap too hard you may get a flat spot in the face of the rivet or deform the chrome face. The official tool has slightly dished faces to preserve the shape of the head.