?Fitment? Fits Most LS Engines From 1999 Through 2016 , Such As L83 Vin C , LMF Vin 4 , LH9 Vin P , LH8 Vin L ; LC9 Vin 3 7 , LMG Vin O , LY5 Vin J , LH6 Vin M , L33 Vin B , LM4 ; Vin P , L59 Vin Z , LM7 Vin T; Vortec Gen III , Vortec Gen IV , And More . ?Stability?Dokili Valve Springs deliver increased valve train stability and a much lighter valve train. This is achieved with less spring pressure for better valve control and reduced weight of both the spring and retainer. ?Durability?The unique designed shape handles valve train stress more efficiently to eliminate damaging harmonics and increases high RPM horsepower and durability. The oval/multi-arc wire shape places the maximum area of the wire at the point of highest stress to handle valve train stress more efficiently and allow better heat dissipation for longer life. Because of the unique design, the valve train can handle more RPM and more aggressive cam profiles. ?Note?Handle springs with care. Never place in a vise, grab with pliers or hit them with a hammer. This will damage the surface of the spring, which will cause it to fail.Do not clean springs with acidic or evaporative cleaners. This causes rapid drying and promotes the formation of rust on the surface, which can cause catastrophic failures.