It sounds funny but I have a rolling tool cabinet that came with crumby castors and I roll it to the machines I calibrate so I wanted it to roll well. I replaced all the castors with high quality ones they actually roll well. I didn't decide to buy the locking ones mostly because it is very heavy and was so hard to roll before. It rolls very easily and if you bump it it rolls away. The building I work in is 120 years old converted warehouse... I often am chasing it down the halls... LOL I could just see bumping a rack and having it move far enough to pull the probes loose or topple the t-stats...