These casters are high quality and each one has a locking brake. Negatives: Each caster has to be put on with 4 screws...each of these screws is actually a 4 piece set of screw, nut, and 2 washers.....and all of these are very small, so assembly is very tedious and would be difficult for a man with large hands to assemble. Another important consideration is that these casters will only correctly support standard or heavy duty crates. I had purchased 4 XXL lower cost crates, which use thinner wire, and after spending about 30 minutes putting all 4 casters on the bottom of it, just to then find out that the crate was too flimsy to be supported at those 4 points of contact (the casters) rather than being fully supported by sitting flat on the floor. The bottom of the crate arched up so much that the area where the tray was supposed to slide into was closed up completely and unusable, and the whole crate was also "bouncy".... so these need to be under stronger crates. I took these 4 off and moved them to another stronger crate, and they work like a charm!