Concrete roller meters use the rolling method of measuring entrained air in any concrete. Roller meters come in aluminum or plastic (Volumetair). The lightweight aluminum roller meter simply and accurately measures the air content of any freshly mixed concrete. In addition, the aircraft grade cast aluminum meter resists corrosion from concrete mixtures. The ultra-lightweight plastic Volumetair roller meter weighs two-thirds less than the brass roller meter. It also weighs one-half less than the aluminum roller meter.