This 4" x 1-1/4" flat tread thermoplastic rubber premium standard duty threaded stem caster is quiet and smooth rolling. Thermoplastic rubber wheels are floor protective and easy to start. The caster is retained with a 1/2-13UNC x 1-1/2" threaded stem. Our 22 Series premium standard duty threaded stem casters feature high quality, durable and quiet wheels and optional total lock brakes. A variety of mounting options are available as well. High quality wheels feature precision ball bearings and optional delrin bearings, making these casters versatile and universale.