3M Betapure BK Series Filter Cartridge Absolute Rated BK20Z8300G1SFB Acrylic/Cellulose 20 in. 30 Micron Grooved Surface 222 O-Ring & Flat Cap Fluorocarbon O-Ring 15 per case.

Betapure BK series is a truly absolute rated, rigid (non-compressible) resin bonded filter cartridge. The absolute-rated rigid structure of Betapure(TM) BK series filter provides consistent performance and will not unload or lose filtration efficiency throughout its usable life!