This is the best dolly available for professional use. It is virtually impossible to tip a loaded dolly since the bucket platform is only 5/8" above the floor, giving this dolly the lowest center of gravity of any on the market. The exclusive 5" diameter center hole permits a user to hold the bucket on an angle for easier material access from a near empty bucket. Has five casters for easiest moving and turning. The dolly has a reinforced design and is molded from plastic. Casters have single wheels mounted on ball bearing swivels for a 300 lb. dolly capacity.