Rivet nuts are made from heavy duty iron which provides strength and long service life. With open end,small flange,round hole,threaded inner wall and partial anti-skid ,these flat head rivet nut has a good performance of fastener function. Each size includes many pieces of rivet nuts so you don' have to go to searching rivet nuts for a while. Comes with a rivet and many mandrels and nosepieces for convenient riveting. Package weight:1256g/2.8lb Color:picture color Material:steel,aluminum alloy Package Contents: 20 * M-3 Rivet Nuts 20 * M-4 Rivet Nuts 20 * M-5 Rivet Nuts 10 * M-6 Rivet Nuts 10 * M-8 Rivet Nuts 5 * Mandrels and Nosepieces(M-3,M-4,M-5,M-6,M-8) 1 * Rivet Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.