Model DA disc aerator from BlueLevel Technologies is a 4-inch diameter aerator using Food and Drug Administration-compliant silicone in blue or white. The hardware is constructed of zinc plated steel, and the unit can be mounted from the inside or outside of the bin. Each Model DA disc aerator can aerate an approximate 20- to 24-inch diameter area, designed for periodic operation using higher 20-30psi air pressure than standard rectangular pads.