This is a Manfrotto 231ARM Hand-Grip Sliding Support Arm
replacement, or an auxillary Sliding Support Arm designed to fit onto the Manfrotto 231 or 231CS (old #3381) Column Stand, or any column or pipe of 1-1/8" diamter.
Hand Grip action release allows your stud mounted light to slide, then lock into position by releasing the handle.
What's in the Box
Manfrotto by Bogen Imaging
231ARM Hand-Grip Sliding Support Arm