The San Tan Tactical ultra grip kit with forward assist features STT's signature Ultra Grip texture. This texture provides excellent grip for use with or without gloves, making this kit a must-have for your custom build. All Parts fit Mil-Spec upper and lower receivers. The STT Ultra Grip Kit with Forward Assist includes the following parts: Ultra Grip Extended Mag Release Button. Ultra Grip Bolt Catch. Ultra Grip Forward Assist with Spring.