Seachem The Bag is an innovative welded filter bag with a durable non-stitched seam. It has a 180 micron mesh, is resistant to bleach, caustics, and acids, and comes with a convenient resealable locking closure. Seachem The Bag is available in a convenient 13x25.5 cm (5x9 inch) size. It is ideal for all filtration products and has an exceptionally long life.Unlike stitched seams, welded seams are not subject to degradation from exposure to bleach, caustics, acids, or other harsh environmental exposure likely to take place during regeneration of filter media. Caution should be excercised, however, to avoid overfilling or over-packing as welded seams can be forced to separate by excessive pulling forces.