simple , durable tripods for instruments such as those employed by surveyors , cameras , telescopes , laser - based measuring devices , etc . these tripods feature a tripod head which is a single piece of material and pivotable legs with a one - piece foot and a side - by - side or triangular array of hollow posts which provides strength and rigidity at a low weight . the tripod components are fabricated principally from colorfast , impact resistant , synthetic polymers which are : dimensionally stable under varying ambient temperatures ; impact resistant ; resistant to chemical attack and ultraviolet degradation ; and , in the case of components which move relative to each other , self - lubricating . the tripod legs may or may not be extensible ; in either case the tension between each tripod leg and the tripod head is independently adjustable . stability may be promoted by rolling bearings which are located at the upper ends of the tripod legs and are seated on complementary bearing surfaces in the tripod head . a novel overcenter type , cam - operated clamping mechanism , also useful for other purposes , is employed to lock the tripod leg assemblies together in the wanted relationship in those tripods which employ legs with one or more extensible leg assemblies . either spike or tilting shoes may be provided to stabilize the tripod legs on the tripod - supporting stratum ; a battery hanger may be attached to one of the tripod legs ; and a novel arrangement coupler the instrument attaching bell of the tripod to the tripod head so that the bell will not be lost or misplaced .