A T-shaped support member that can be used with a bed frame or bed rails to provide support for a box spring and mattress. A leg assembly is affixed to the support member and is used to support the cross member. The leg assembly includes a housing having a leg that extends downwardly from the support member to contact the floor on which the bed frame or bed rails are located. The length the leg is extendable from the support member is self adjusting by a mechanism that can be twisted to an unlocked position to drop the leg downwardly quickly to contact the floor and then twisted back to lock the leg in that extended length.