Non-threaded stem casters include a variety of rigs that have a grip ring or square stem for mounting. We currently offer 7/16" grip ring stems but soon we will have available most of the other main sizes of grip ring stems. The square stem size that we have is .87" x 2", but these two we hope to expand in the near  future. We also have some stemless swivel and scaffolding casters. The wheels available range in size from 2" to 8" and come in a variety of different material types. Choose from Chariot chair casters, Polyon aluminum, Thermo-pro, Nomadic, Polymadic, Duralastomer, Polyon cast, and Shepherd Vipor wheel.