JE Machine Tech .223 Caliber Silent Recoil Spring System Black. The Silent Recoil spring eliminates virtually all the friction and vibration typical of the standard buffer components resulting in a much smoother cycling rifle with none of the cheese grading sound typical of the standard buffer components. Specifications for JE Machine Tech .223 Caliber Silent Recoil Spring System: Manufacturer: JE Machine Tech Color: Black Finish: Matte Fabric/Material: Aluminum Gun Make: AR Platform Gun Model: AR-15 Weight: 0.35 lb Projectile Caliber: .223 Caliber Package Contents: JE Machine Tech .223 Caliber Silent Recoil Spring System (1) 28 coils spring What firearm models does the manufacturer say JE Machine Tech .223 Caliber Silent Recoil Spring System is compatible with? The manufacturer suggests that JE Machine Tech .223 Caliber Silent Recoil Spring System is compatible with AR-15JE Machine Tech PS-BFSC4: .223 Caliber Silent Recoil Spring System Black