For decades Eaton's SNAP-RING filter bags have been an affordable solution for process applications. Made under ISO 9001 quality control standards, SNAP-RING bags are manufactured to be reliable bag after bag. A size 04 filter, bag N-25-P04S-50 has a retention rating of 25 microns. This bag model is constructed using heavy-duty sewing techniques. The felt is nylon with a carbon steel ring sewn in the top. This ring prevents bypass by sealing against the filter housing seat - whether your housing is Eaton brand or another make. This Eaton filter bag comes in box quantities of 50.