The STS (Short Throw Safety) AR15 Stripped Lower Receiver is the perfect lower to start your build. Custom designed markings accept short-throw safety selectors while maintaining mil-spec dimensions and correct component interface. Selector markings will work with 45, 60 or 90 degree safety selectors.
STS lowers are marked and milled to accept short-throw safety selectors, but will work with standard selectors as well!