The bags fit perfectly into my Siemens Big Bag vacuum cleaner 3l. At first I was skeptical about whether it is because the right people, because even the box-connecting part (whatever they call it) looks quite different from the original, but it sits and is serving. I'm very satisfied, 10 bags to keep forever and the price is a joke, currently about 86 cents a bag. For comparison: Original bag (only available in 4-pack) cost about 2.50 per bag.