Great filters, I've tried buying a huge roll of filter floss, but trying to cut it to size was a chore, and it was thin and limp, a load of rubbish compared to these , I will say one thing though. I do not throw them away after one week. That's ridiculous, expensive and totally unnecessary. I take it out weekly, and gently swish it around in some tank water I've removed, don't wring it, just squeeze gently, and all the muck comes off, and pop it back. I can get well over a month out of one filter. Replacing it every week is, in my opinion, a manufacturing ploy to get more of your hard earned money. Well they'll have to wrench my money from my cold dead fingers if they think I'm falling for that!! Great filters though!