HYDRA BIG PM is a single stage self-cleaning filter with a stainless steel mesh-filter for effective removal of sediments. The BIG models have bigger inlets/outlets (1 1/2″) for use in applications where large flowrates are needed. Easy and quick cleaning, thanks to the exclusive system with back-wash in counter- current. This model includes 2 brass plugs on top of the housing for installation of additional pressure gauges (sold separately) to conveniently measure water pressure before and after the filter. HYDRA BIG PM can be installed as a pre-filter before your water tank to keep it clean from sediment and sludge or before your existing water filter to save on maintenance costs. Very easy to operate – simply open the valve to flush accumulated sediment out via the drain funnel.