When you need to change or upgrade your Valve springs
2 Washers and Hex nut
1 Laser Cut steel Tool
This Laser Cut Steel Tool works on LSX base Engines in Trans Am, Firebird, Camaro, Corvette, GTO, Grand Prix, Bonneville, Trail Blazer, Envoy and ALL LS1 LQ4 LQ9 4.8, 5.3, 6.0 Liter GM Silverado GMC Sierra Truck Engines. I recommend purchasing a cylinder pressurizing hose along with this tool. I do not recommend this tool for heads with offset valves, this tool need to be straight with the cylinder head.