Olivier P. am 25.04.2022: I think it's a must have, when purchasing the 2217 I highly recommend you purchase a few of these, they are the true replacement part meaning it's the same EHEIM quality as the one that come with the canister. By having multiple of these inside your canister, if like me you customize the foam you use, you can safely have foam and polyfil at the bottom of your canister without having it crushed by the Bio media that sit on top of it.
As always, I receive these items from Aquaristik perfectly packaged.
