For a Single AR-15 / M4 Carbine:

• Made in the USA and 100% quality inspected by hand for proper function.
  
• Constructed from certified USA made chrome silicon spring wire
• Heat treated, stress relieved
• Provides consistent spring pressure for hundreds of thousands of cycles (estimated 750,000+)
• Greater resistance to heat & high stress cyclic rates
• Improves operation, long-lasting performance
  
• Consistent pressure reduces bolt bounce
• Significantly reduces the perceived "twang" noise which is common during firing
  
  

This item is for ADJUSTABLE length M4 style buttstocks.

Rifle-length recoil springs for full-sized fixed buttstocks are available HERE.