"Tow Tuff portable trailer dolly is ideal for easily moving trailers for service and maintenance around the workshop, marina, and yard. Trailer couplers attach to a 1-7/8"" ball, adjustable from 16.5"" to 25.5"" high with a locking pin. Tow Tuff trailer dolly features a 30"" wheel base with (2) 12"" solid rubber tires and (1) 8"" swivel caster for steering - Maximum 800 lb capacity."