H Series heavy-duty casters feature a bolt-on directional lock. These models are now manufactured with notches to make it easier to install and use the bolt-on style directional lock. The lock is bolted on underneath the top plate, using the top plate mounting bolts. When engaged, it converts the swivel caster into a rigid or fixed caster. The casters feature either a roller, taper roller, or precision ball bearing and are available in diameters of 4?, 5?, 6?, 6-1/4?, 8?, 10?, and 12? with load capacities ranging from 330 to 3,300 lbs. Swivel models are fitted with oblong top plates and can also be ordered with wheel locks or brakes.