ROYAL RA Series Filters Royal RA series air filters are used in a variety of applications for removal of particulates from air and gasservice. Cartridges are available for air intake systems on engines, compressors, blowers, and turbines. Replacement cartridges ae also available for dust collectors and material handling and conveying systems. RA cartridges are constructed of the finest quality components, including galvanized or plated metal components, phenolic resin impregnated, pleated medias, fire retardant medias, and synthetic medias. Both round and panel type cartidges are available. Replacements are available for many major manufacturers.