Apparatus for adjusting relative positions of first and second members

摘要

Apparatus for adjusting a first member relative to a second member comprises a button with two sets of teeth and movable between first and second positions. When in the first position, both sets of teeth engage sets of teeth carried by the first and second members to prevent relative movement of the first and second members. When in the second position, one of the sets of teeth carried by the button disengages one of the sets of teeth carried by one of the first and second members to allow relative movement thereof.