The Pentek PO25G4S Polypropylene Felt Filter Bags are a Size #4 which means they are 4-1/8 inches in diameter and 14 inches in length. The bag filter area is 1.0 square feet. Pentek PO25G4S Polypropylene Felt bag filters are compatible with a broad range of corrosive fluids including organic solvents, oils, acids, alkalis and microorganisms. The Pentek PO25G4S Polypropylene Felt Filter Bags can withstand temperatures up to 200and#194;and#176;F. There is an initial pressure drop of less than 0.5 psi for the maximum rated flow at 68 degrees Fahrenheit. Differential pressure of 15 psi indicates the filter bag needs to be changed.