Smooth Bore Bushings Heyco offers Smooth Bore Bushings designed with a large radius hole and an extra internal insulating sleeve, creating a smooth bore to prevent locking fingers from protruding into the ID of the bushing. It protects wires by eliminating sharp edges, absorbing vibration, and supplying cushioning. This versatile component also protects through-holes and can be used for rotating shafts. Heyco Smooth Bore Bushings are made of 6/6 nylon, carry a 94V-2 flammable rating, and are ideal for a variety of applications, such as combiner boxes, appliances, control panels, medical equipment, and more. UL recognized under File E15331 and CSA certified under file LR8919.