Medium Strength therapy putty which offers a complete range of resistance exercises Build up the muscle strength or grip in your hand or wrist following injury. It was so much fun we couldn't put it down. Clean, non-toxic, non-oily and bleed proof therapy putty leaves no colour or residue on the client's hands. It will not fragment, separate or stick to the skin. Designed to meet a wide range of strengthening needs, putty can be squeezed, stretched, twisted or pinched. sistance levels required for hand exercise programmes.