The Apollo PEX Combo PEX Copper Crimp Ring Tool is a 2-in-1 tool designed to secure 1/2 in. and 3/4 in. copper crimp rings (not included) into place within PEX piping systems. There are no loose components, jaws to change or adjustments to be made to create either size connection. Connections may be checked for security using the Go/No-Go Gauge (included). The Apollo PEX system is a comprehensive piping system comprised of brass fittings, poly alloy fittings, manifolds, valves, fasteners, tools and tubing designed for implementation in water delivery systems, simple or complex.