Compatible Models: 413 Replacement Air Filter is Designed to perfectly fit Aprilaire 413 Whole House Models 1410, 1610, 2410, 2416, 3410, 4400; NOTE: Not Fit for 1413 Upgrade Kit (Model 2400, 2140). Actual size is 16 x 28 x 4 inches . Nominal size is an industry standard filter size system to help you easily identify the correct replacement filter, not necessarily the actual size,The size of the filter installation should match the actual size (16 x 28 x 4 inches) Our filters provide a superior solution that seamlessly integrates into your existing system without any modifications Revolutionary innovative design (patented):The unique foldable design,by using 4 bendable metal strips, the filter can be easily folded and unfolded, Replacing, installing the filter is a breeze. It also provides good support under high air intake and can be easily stored when not in use. By using four sealing strips on top and bottom, the amount of air bypassing the filter can be minimized to provide better sealing effect. Easy to install: Unpack, Unfold the filter, Slide in, Close the door, It's done, without aligning the upper and lower Interlock Rail System, No assembly cardboard or metal strips and screws This innovative design offers a significant improvement over traditional filters.