For the cost conscious riders who value the ride of the larger drums.
The Alloy 4.5 Rollers are the flagship of the Kreitler line. Beautifully machined and perfectly balanced, the Alloy 4.5's are the quietest and smoothest rollers on earth. Some would call the Alloy 4.5's the "Rolls Royce" of rollers. We tend to agree.
The Challenger 4.5 Rollers use the same 4.5" machined aluminum drum cylinder as the Alloy 4.5 Rollers, but use Poly end caps for a more economical option.