4GRCP - 4" Groove lock coupling/clamp4" Rigid Groove lock coupling clamp Rigid Groove Couplings provide an inflexible connection that produces straighter alignment of pipes with no sag and very little movement in your plumbing system. Works well for unsupported pipes and valves. Rated at 300 maximum PSI. Gasket included. Application: Designed for applications requiring moderate internal pressure or where weight is a factor such as general purpose, mining, irrigation, and compressed air