Tilbakeslags ventil til luft pumper .  meget viktig for att ikke vann skal renne  utav  akvariet  Check valves are used to prevent water flow back up the air tubing and thus potentially damaging the air pump. AQUARIUM ACCESSORIES - CHECK VALVES & VALUES   Check valves are used to prevent water flow back up the air tubing and thus potentially damaging the air pump. This product is a three-pack blister pack.