Rock-N-Roller R5CSTR/Y/B Replacement G-Force Caster with Brake (for R8 and R10 Multi-Carts), 5" x 1.25" Replacement caster with brake for Rock-N-Roller cart models R8 and R10 Caster brakes assist loading on inclines Polymer hub bonded to soft TPR tread All casters are sold indvidually