Specification:Material: 65# manganese steelSurface Finishing: BlackeningSize(inner dia.*outer dia.*thickness)& Quantity:3*9*0.25mm 30pcs4*12*0.25mm 30pcs 5*12*0.25mm 40pcs6*16*0.25mm 50pcs8*17.5*0.25mm 50pcs10*20*0.25mm 40pcs12*25*0.25mm 20pcsWeight: 169g / 6oz (approx.) Features: Made of 65# manganese steel, these lock washers are durable and sturdy. This set contains many different sizes of washers to meet various need. There are total 260 lock washer that you may use for a long time. All washers are well packed and assorted in a plastic box for convenient storage.