Ultem Replaceable Inlays for sale are designed for additional customization of Knuckle Dusters Edc Swampy. Ultem (aka Polyetherimide or PEI) is the ultra trendy material in the U.S. world of EDC today. It has a very nice and recognizable amber-to-transparent color. The Inlays are attached to the Keychains using magnetic mount. Customization with an Ultem Inlay will make your Single Edc Knuck really cool.