Also referred to as Roll, Tension and Expansion Pins. Hollow and slotted lengthwise to create tension, these self retaining Spring Pins are made of Type 420 Stainless Steel.Stronger than 18-8 stainless steel, more corrosion resistant than zinc-plated and plain steel. Magnetic. Minimum Rockwell hardness is C43. They are installed by two easy operations, just drill and drive. Useful for many purposes, including electrical connectors in patch board circuits, terminals, fixtures for wire harness, actuators for drum, to secure pulley or gear to shaft, hinges, positioning, studs and many others. Superior to and used in place of drive pins, taper pins, collar pins, etc. They permit a wider tolerance because of the flexibility. Tapered ends make starting easy.