Rexer Free Spin F Model Rollers Features: Travel Ready (easily fits in a carry-on bag) Seated roller to keep rear wheel secure for high speed sprints 20", 24", 26" and 700c wheel compatible (Knobby tires not recommended) Rubber feet, safe for indoor and outdoor use Roller weight capacity up to 3,500 lbs Operates smoothly and quietly 3/16 Aluminum side rails Aluminum end caps color matched to side rails Hard anodized roller tubing Steel shaft ABEC 1 bearings