The Alloy is the top-of-the-line when it comes to rollers. The all aluminum drum construction, aluminum end caps and shield bearings are perfect for high rpm continuous pedaling. The drums are 4.5" x 15" and perfect for use with the "Killer KOOL Headwind" and Flywheel. The Alloy has a black epoxy powder coated frame and an orange belt. The Standard Kreitler Frame is adjustable for wheelbases from 31.5” to 48.5”.