RIM AN (AM) 20 406x21 ACME UD CARBON TBLS DISC 36 RDUnidirectional carbon BMX rim designed for use with disc brake or as a brakeless front wheel. Full Toray T700 carbon fiber composite material. Drilled for both Presta and Schrader with included plug for unused valve hole. 220lb rider weight limit. Race use only. Item Specifications: Size, 20in, Width OD, 28, Drill, 36, ERD, 390, Wall, Dbl, Valve, PV/SV, Model, Acme UD, Profile, 20, Tire Compatibility, Tubeless Compatible, ISO, 406, Width ID, 21, Brand, Alienation,.