Finest quality coil springs, controlled-tension wound for smooth operation without binding under compression. “Over-Pin” springs are designed to function over gun pins and plungers; “In-Hole” springs are made to fit inside restricted areas. “IN-HOLE” MASTER KIT - Combines Kit #1 ID-12 and Kit #2 ID-12 for a total of 12 springs for in-hole use. SPECS: High tensile spring wire. 12' (30.5cm) long.