The AstroFrame holding frame is specifically designed for gel or gasket seal AstroCel I HEPA filters. Made with 14-gauge all welded construction (galvanized steel or 304 stainless steel), AstroFrames are made to deliver maximum enclosure integrity. Each frame is fitted with four removable, pressure bolt latches to produce sealing pressure. A flat, wide surface sealing flange is provided for gasket seal filters and a knife edge flange for gel seal filters. Self-contained prefilters are also available and are held in a separate frame attached to the AstroFrame to permit replacement without disturbing the AstroCel filter. AstroFrame holding frames are factory drilled for convenient field assembly. They are 13-1⁄2" in depth without a prefilter, 15-1⁄8" in depth with a prefilter.