The casters Spin and roll freely, and have metal locking mechanisms that lock positively and no plastic involved to worry about breaking.
The wheels are a nice rubbery material that roll smoothly on my rug or hardwoods.
The kit has 4 casters, and came with screws and washers for mounting and they installed without any problems. There was also a screwdriver included.
I'm very happy with the function and quality.
My easel is rolling smoothly now!