FlatSider XR7 Shoulder HolsterFlatsiding works so well on AKER belt slide holsters, they adapted it for shoulder holster carry! What does that mean for the 107 FlatSider XR7? In the molding process, AKER uses a customized method to ensure that the back of the shoulder holster is flat against your body and the fine contouring of the weapon details comes out on the front. This creates a stunning look and provides extra friction retention while ensuring that your holster stays