This kit contains two replacement Shok-Buffs and one heavy-duty recoil spring. Two of the most effective and inexpensive ways to maximize your 1911's long life and accuracy are to use Shok-Buffs and quality recoil springs. Theses drop-in parts help eliminate the battering of critical components. To ensure maximum protection, recoil buffers should be replaced every 1,000 rounds and recoil springs every 2,000 rounds. Includes 1 Heavy duty 18.5 pound recoil spring and 2 Buffers.