Although I use a shield of shield for a long time, it is necessary to replace it periodically with this intake valve, but it is good to purchase it with one piece although it becomes useless except for the absorption can. Regularly ordered two sheets and used one piece as one reserve Continuous use as a spare has come handy.
I purchased it as a replacement part for the dustproof mask DR31C2. For this mask, this intake valve is a consumable item, but it was not handled in a nearby home center or a work shop. I bought it knowing that it is sold in monotail. Replacement work is easy. Just remove the worn valve and replace it with a new valve. The dust mask revived thanks to this valve. It is recommended to purchase several valves in conjunction with purchasing the dust mask DR31C2.
When installing, pushing the main body strongly will break the main body. It was repaired with instant adhesives. Even though there was a long time ago, the neighborhood home improvement center did not sell anything.