The Bear Song IV butterfly knife is collaboration between BladeRunnerS (BRS) and Bear OPS. It is a lightweight flipper that is designed to be your go-to everyday carry knife. The B-400 model features aluminum handles with stainless steel spacers and a swappable latch. The pivots have phosphorus bronze washers. The satin finished 14C28N stainless steel clip point blade has a double tang pin design for great performance.