2 COMMENTS

  1. I agree with gnomes, and another thing, sometimes they have windows where you can see if it is full or not. Like when it gets to that area, time to dump it. I hope this helps ya.

  2. I would assume most work by measuring the flow of air. As it fills less air gets thru. I had one that a button would turn red when it was full. And if the filters needed to be cleaned the red button would pop up even the canister was not full.

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