4 Inch Thermoplastic Rubber Wheel 5/16 Inch Threaded Stem Caster Wheels are available in non-marking polyurethane, thermoplastic rubber and soft rubber, excellent for carpet, concrete and tile floor surfaces.5” threaded stem.Also, the innovative expanding stem, that can easily adapt to the inside diameter of an opening, allowing for a secure fit in round or square tubes. Supports up to 125lbs.