I breed rodents and build shelves to house them. These racks weigh about 80 pounds each and require 4 wheels each. I started using these wheels about a year ago and have kept buying them as more racks have been built. Today I have 30 racks with these wheels. Everything holds tight, rolls easily, doesn't squeak and doesn't leave marks on the floor. I have fibromyalgia and moving heavy objects can be difficult for me. These wheels save lives. Several times the rat carelessly jumped out of the open tub only to run under the shelves. Luckily, with these wheels, it's very easy to quickly move the shelves away from the wall, making retrieving the rats less of a hassle. Yes, I have a strange business, but rodent sales are going well. lol Please upvote my review if you found it helpful