The coffee valve (one way degassing valve) permits the CO² out meanwhile prevents the air to get back into the packaging to keep freshness. And it can be prevented from the break up caused by inside air during the shipping or storing.
Coffee Valve WJ1901 Series (with filter)
Coffee Valve WJ1902 Series (without filter)
Coffee Valve WJ2302-CPE (without filter)
Coffee Valve WJ01P (square)
Coffee Valve WJ02P (circle)