"Kit of 2 pieces of 4in swivel casters and 2 pieces of 4in swivel casters with brake kit
4"" x 1-1/4"" Soft blue rubber tire and nylon hub
Heavy duty steel mounting plate
Load capacity: 155kg/350lbs, Mounting plate size: 3.13"" x 4.14""
Full double ball bearing swivel assembly"
https://ca.tchweb.com/collections/casters