US1D is a line of products developed by World Products. It is a range of automotive engine parts designed to increase engine performance and durability. The US1D line of products includes camshafts, lifters, crankshafts, connecting rods, pistons, and other components. These are designed to be used in modified, high-performance engine builds. All US1D components are designed and tested to maintain a high level of durability and performance over time to ensure reliable operations and performance.