Metric Replacement Inserts. Recoil helically wound wire thread inserts can be used to strengthen threads, giving applications a longer life. Each insert shares the load over the entire bolt and hole, improving holding or pull out resistance, providing a more even distribution of load and stress. Recoil inserts are generally made of type 304(18-8) stainless steel wire rolled into a diamond shape cross-section. Lightweight yet robust design gives superior holding power Quick and simple installation process Length is 1.5D