The ZTEC WB Series Membrane Filters, manufactured by Graver Technologies, features its genuine qualities such as its absolute retention ratings that ranges from 0.2 to 1.2 micron, FDA-listed materials of construction, lab-validated bacterial retention performance, reliable contaminant-removal technology and a high-level class of USP tests for plastics ( Class IV ). These filters have a high surface area and a newly-developed polyethersulfone membrane filter cartridges for beverage appliation.