Pre-Filters are made of l-1/2” thick PVC construction and are absolutely moisture-proof, rust-proof, and corrosion-proof. Pre-Air Filters for Double or Single Vacuum Line include automatic drain valve assembly, gasketed removable lid, stainless steel screen, and washable filter with baffle. A plug is included to seal off the unneeded outlet in single configuration. Pre-Air Filters are packaged in 350-lb. double-wall corrugated box with expanded polystyrene corner pads. UPS shippable. Vacuum Pre-Air Filter with 3" inlet for pump connection and 2 x 3" vacuum line connections.