Irwin Snub Nose Bi-Metal Safety Knife Blades The snub nose blade design helps to reduce the risk of accidental puncture wounds. Shatterproof bi-metal blades combine the best of two metals, electro-welded together for superior performance and safety. Bi-metal blades stay sharp up to 3 x longer than carbon steel blades. Irwin Snub Nose Bi-Metal Safety Knife Blades. Qty: 50. IRW10505824