Some industry protection products are pretty straight forward. A cable gland protects a cable where it is secured into a piece of equipment. A swivel caster is less straight forward, and actually fits better into the category of a finishing product. Swivel casters are used to mount wheels to forks in things like shopping carts so that they can be turned and navigated.
When you work with lots of different protection and finishing products it can be all too easy to get confused, or mix up which product does what. Every now and then it is a good idea to refresh your memory and brush up on the uses for all of your tools.
1. Protect screws.