Hi Kela, these are made with soft rubber wheels and are intended for use on hard surface floors.
This product is 4.625 inches tall.
the load rating is 80-lbs per caster. 4 casters x 80 lbs (each) = 320 Lb load capacity.
we cannot advise on what length of screws to use.
They should work fine on most floors and carpets, but it would ultimately depend on the height of what is considered medium length carpet.
They are built for indoor use. They can be used outside but if they are not used on a smooth surface they may damage easier.
There are no locks
Each caster has an 80 lb load capacity. Polyurethane.
The price is $5.65 for a 2 pack.
The plate dimensions are 1-1/4 in. x 2-1/8 in.