Door weatherstripping: is this slot a kerf or something else?

Ultimate Guide to Q-Lon Door SealWeatherstripping with Kerf Mount kerf slot Weatherstripping for doors with Kerf slots Silicone seal is longlasting and high durability Comparable to ZERO 8004N machine slot online This slot is meant to accept the weatherstripping fin that kerf weatherstripping have Kerfs are usually cut during the manufacturing process of

bonanza billion slot demo New 8 Meters Kerf Weather Stripping Seal Strip for DoorsWindows Frame Q Foam Card Slot Installation Sealing Gap 5 to 16mm Feature: