CRL Heavy-Duty Steel Frame Glass Dollies can be used indoors or outside for transporting heavy plate glass or insulated units. The large 8" (203 mm) wheels will roll smoothly, even over rough surfaces. Constructed from a rubber lined, 3" wide x 1/4" thick (76 x 6 mm), heavy steel channel which supports the glass 5-1/2" (140 mm) off of the floor. Wheels are set 12" (305 mm) apart to provide stability.