Like an extra pair of hands, this job-site helper holds ductwork in place with clamps and a chain during installation until permanently secured.  Temporarily suspending duct or venting from any joist is fast and easy.  Double-ended keyhole also allows easy chain adjustment and locking in a horizontal clamping position, required for engineered joists, without the need to tie the chain around the clamp.  Formed teeth hold the clamp securely in place on joist.