Colson Brand heavy duty castors. Kick stop bracking and swivel stop. Twin soft tread wheels to prevent marking delicate surfaces. Wheels 100 mm diameter. 55 mm across width of wheels. 12mm x 20mm threaded bolts. KIck lock stops wheel and also stops the wheel from swivelling around. quite a versatile idea. This auction is for one set of 4 wheels. I have 12 wheels in total so just ask if you want more than one set.