The device utilizes a thruster cylinder driven by a enlarged knob and terminating in a thruster plate to clamp to a support. Provision is made to attach a device to the clamp through a rotating index wheel which can lock the device by receiving a tang from a trigger lever at a selected increment of rotation. A second embodiment has two index wheels so that the attached device can be displaced in one of four directions to avoid conflict with other devices on the same support. The second axis is normally used to return a displaced device to an upright orientation.