Designed primarily to haul fly ash, soda ash, and plastic pellets the 1680 4-hopper is the lightest pneumatic in the industry due to the design and the all aluminum construction. The “R” model has a round cross section rather than an elliptical cross section. The elliptical cross section is always trying to become round (competitors models) while the Beall design is already round. This design reduces the flexing of the trailer and enhances the work life of the trailer and reduces potential maintenance issues.