Abstract: An adjustable support assembly adapted for being releasably secured to an elongated support member comprises a clamp body member having a first lateral side for engaging the surface of the support member and a pair of pin members secured to and extending outwardly from the first lateral side of the body member. The pin members are generally parallel and spaced a distance greater than the width of the support member. The body member with the two pin members form a structure which is generally U-shaped in cross section for receiving the support member. An arm member is pivotally attached to one of the pin members to permit the other end of the arm member to engage the other pin member. Locking means are provided for retaining the other end of the arm into engagement with the pin member and for urging the arm member into clamping engagement with the support member.