A mechanical pipe coupling is formed of segments attached end to end to surround a central space. Each segment has arcuate keys which project toward the central space. Each key is formed of a pair of side surfaces and a mid surface between them. The mid surface is angularly oriented relative to a longitudinal axis perpendicular to a plane containing the segments. When used to couple pipe elements having grooves the angular orientation of the mid surfaces provides flexibility to the joint. A method of joining pipe elements end to end is also disclosed.