One of the benefits of using the bag though is that it will withstand the bleaching process used to refresh the purigen. If you're lazy, like I am, and refresh it in the bag then it's something to consider. Also you need to make sure that any other bag you might want to use will be fine enough not to let the purigen to leak out. Most of the readily available bags are meant to hold carbon and other similar sized media and the openings might be to large to hold purigen.