Model 4 replacement bags are offered in polypropylene, polyester, nylon, and meta aramid materials. Choose from the drop down menus, either RPE or RPO for Rosedale housings, or Ring style bags to fit in any manufacturers' filter housings. RP series top bags offer the best bag-to-housing seal in today's marketplace. Micron ratings are standard grades. Size tab reflects industry trade size bag number. Prices shown are for 10 and 25 piece packaging.