Mine lastedd about 8 hatches
Took me a retake to see that was for me LOL. Ok so eight weeks so that would be about 7 a year.... hum... I found some for $40 including shipping for 10. I am guessing you use them though the whole hatch. I would only use it though lockdown each week..... might last longer. How do you know to replace it? does it dissolve or what?