The screen, of course, is the heart of the Y-strainer and the point where the dirt or unwanted material is trapped. In the case of small sizes (up to 2 inches), a cylindrical wire mesh screen is generally satisfactory if pressure is not too high.  For larger sizes, a simple wire mesh cylinder does not have enough mechanical strength and it should be backed up with a perforated metal cylinder. Stainless steel is the preferred material for Y-strainer screen and is used with almost all Y-strainers regardless of material of construction.