Versatile: Experience unparalleled versatility as the BNVD-40 Battery Pack accommodates either 4x AA batteries or 2x CR123A batteries Velcro Support: Seamlessly integrate the battery pack with your helmet setup using the included Velcro connections, ensuring a secure and snug fit Ergonomic Design: Its ergonomic design offers optimal comfort during extended use, freeing you to focus on your nighttime missions without hindrance Long-Lasting: With an impressive run time of 60-80 hours (depending on battery type and device settings), uninterrupted exploration becomes a reality Durable: Crafted with precision from durable Ultem 2300 material, this rugged pack ensures exceptional performance and reliability in tough conditions