Abstract: An air filter arrangement for use in a heating or cooling system including a frame and a filtration member secured within the frame. The frame is defined by a pair of opposed frame components or halves, which are removably or permanently fastened to one another with the filtration member sandwiched therebetween. The frame itself defines a template for permitting trimming of the filter arrangement to one of number of standard filter sizes. The frame is vacuum formed, which allows the frame to be formed from a thin, sheet-like plastic material, and results in a flexible, yet rigid frame which allows easy trimming by the user and provides a filter arrangement with is lightweight and inexpensive to manufacture.