Swivel Locks are used to lock the Swivel – Not the Wheel. This is accomplished by a “Spring Loaded Plunger” engaging into a slot in the swivel bearing. The slots are located at 90 degree intervals around the swivel bearing. The lock can be engaged in any slot, thus giving you 4 different directions in which to Lock the Swivel. It is best to order the Swivel Lock when you purchase the caster as the ‘Notched Swivel Bearings” are not a standard on all casters. They are, however, shipped when you order the Swivel Lock with your caster order.