Abstract: A framed air filter, comprising an air filter media having a generally rectangular perimeter with four major edges, and a frame comprising four frame portions. Each frame portion of the frame is mounted on one of the four major edges of the air filter media and met with neighbouring frame portions to form corners of the frame. At least one of the frame portions is provided by a frame piece that comprises first, second, third and fourth panels that are foldably connected by fold lines, which single frame piece is wrapped in a generally rectangular configuration so that the fourth panel comprises a forward terminal end that is abutted proximal a rearward major surface of the first panel. The third panel provides a rear wall of the frame portion with an inner edge provided by a fold line connecting the third panel to the fourth panel, wherein the inner edge is bowed.

Abstract: A framed air filter, comprising an air filter media having a generally rectangular perimeter with four major edges, and a frame comprising four frame portions. Each frame portion of the frame is mounted on one of the four major edges of the air filter media and met with neighbouring frame portions to form corners of the frame. At least one of the frame portions is provided by a frame piece that comprises first, second, third and fourth panels that are foldably connected by fold lines, which single frame piece is wrapped in a generally rectangular configuration so that the fourth panel comprises a forward terminal end that is abutted proximal a rearward major surface of the first panel. The third panel provides a rear wall of the frame portion with an inner edge provided by a fold line connecting the third panel to the fourth panel, wherein the inner edge is bowed.