Ronin Gear Skeletonized Stainless Steel Practice Butterfly Balisong Knife trainer Skeletonized Stainless Steel Construction! Ronin Gear's new #215 Practice Butterfly knife with polished handles and a 1.25" thick, rounded, perforated dull blade that is ideal for safe training! LEGAL under most state & local laws as it is a "training replica" and not a functional knife!