A MUST FOR BLASTING WITH #8, #10 & #12 NOZZLES OR SPIN BLASTERS WITH 5/16" AND LARGER NOZZLES IF YOU ARE UPGRADING YOUR BLAST POT WITH THE BIG-BORE™ METERING VALVE, YOU SHOULD ALSO UPGRADE YOUR AUTOMATIC AIR VALVE TO A BIG-GUN™ FULL FLOW VERSION AND BIG-BORE™ UNION END BALL VALVE (SEE COMMONLY PURCHASED WITH COMPONENTS BELOW)