The DY-7 dolly is designed for quiet, smooth and effortless tripod movement on studio floors. All wheel castors utilize non-marking, non-setting polyurethane tires mounted on stainless steel rims rotating on needle bearings. Each wheel has positive locking in both radial & axial rotation with step-on step-off design. Each dolly leg folds from a carrying position to 120-degree lock position with each leg terminating with a positive tripod leg lock (tapered cone) and clamping device.