A universal pressure gauge for your swimming pool filter available in 2 sizes. Most swimming pool filters are fitted with a pressure gauge mounted on top of the filter. The primary purpose of the pressure gauge is simply to indicate how much pressure is building up inside the filter. Monitoring this pressure gauge on a periodic basis is an essential part of maintaining a healthy swimming pool. The filter pressure gauge can be useful in many ways and can help identify and avoid many potential problems saving time, money, and headaches.