Abstract: A retention clip which secures radiant heating tubing to a reinforcing bar or wire used to reinforce a concrete slab. In one embodiment, the clip has a C-shaped body which includes a pair of parallel legs connected by a straight bight. The bight is hinged in the center so it can be bent to bring the free ends of the legs together. A pin on one leg then enters a socket on the other leg and a flange on the pin interlocks with a shoulder of the socket to hold the clip around the tubing and reinforcing element. The clip body has stiffening ribs to enhance its strength and dimensional stability. An alternative embodiment provides a straight clip body having a central hinge joint and two elbow joints about which the body can be flexed to bring interlocking ends together. Each elbow joint includes opposing pairs of lugs which provide stability. A block on one side of each elbow joint enters a groove between the opposing lugs to lock the joint against sideward swaying.