Black Derlin (Acetal) wheels are very durable and lightweight. A set of wheels come with bearings and crush tubes. Axle is not included but is available. The wheels are available in 3 different sizes. The small wheels measure 2.250 in diameter by 1.00" wide, the medium wheels measure 2.3" diameter by 1.325" wide, and the PMFR old style large wheels measure 2.9" in diameter by 2" wide.