The Vivitar tripod dolly securely clamps to any camera tripod, allowing for rolling a tripod on a smooth hard surface.  This dolly includes 2.5" hard rubber wheels and locks.  The dolly folds easily for storage in the included zippered carry case.  Adjustable screws allow you to securely attach tripods of all sizes.  Locking metal pins and safety latches help prevent wobbling and keep your tripod secure.