API SPEC 5CT:2025 delineates the technical specifications for the supply of steel piping products, including casing, tubing, and pup joints, as well as coupling stock, coupling materials, and auxiliary materials. It details the dimensions, weights, and wall thicknesses of the products, along with the grades and available end finishes. In compliance with API 5L, pipe products may be procured as casing in accordance with API 5C6 guidelines. Additionally, by mutual consent between the buyer and the manufacturer, this standard may be extended to cover other plain-end pipe sizes and thicknesses, beyond those explicitly outlined in API 5L.