Lightweight Aluminum Easy wheels with 2 pcs. ball bearing Your B will move more smoothly than before and with STYLE And it is lighter and stronger than Brompton Ezwheels upgrade! Features: Lighter than B upgrade EZ wheels (63g vs. 76g) Dia: 60mm. (Two titanium M6 screws) Custom durable thick hard rubber tires for perfect fit and shock absorption. Compatible with MiniMODs X-Roller ezwheel extender and Brompton rear rack (please specify during checkout, different screws required). Artistic yet lightweight design reminiscent of sports car wheels. With Industrial Ball Bearings, much better to roll under load and are durable. Diameter 60mm