The Kreitler Alloy 3.0 Rollers have approximately 40% more resistance compared to the 4.5 rollers, offering the best combination of resistance, cost, and portability. When it comes to training indoors, the Kreitler Alloy Rollers are without equal in improving your spin, balance and form. Kreitler drums are made from high quality aluminum, lathe-turned to within .002" for smoothness, and anodized for a long-lasting finish. They spin virtually without resistant on instrument quality bearings. The Kreitler Alloy 3.0 Rollers features 3 inch alloy drums with alloy end caps and 15 inch roller frame width. Lifetime warranty.