The AAFG02 Archangel Vertical Fore Grip - Full Size features an O-ring protected internal storage cavity, airtight to depths of 66 feet. This cavity allows for easy access storage of spare parts, batteries and other items. The fore grip is made from high strength, impact-resistant proprietary blended polymer. Precision molded to meet MIL-STD 1913 rail specifications. Easy to install and remove, no tools required. The special polymer formulation provides protection against barrel heat. The polymer is impact resistant thanks to a scientifically formulated compound providing superior strength.