Backstrap sleeve slides down over the top of the magazine and fills the gap between the bottom of the grip frame and the base of the magazine. This mid-sized sleeve for backstrap 1 is for your Springfield XD-S with a 3.3"-4" barrel chambered in 9mm. Type Magazine Sleeve Model Backstrap Sleeve Finish Black Series Sleeve for Backstrap Caliber 9mm Luger Capacity 0 Material Polymer Brand Fit Springfield Armory Model Fit XD-S