Forget the countless trips to the store purchase batteries, the pulsar PB8I power bank is a 5100 mAh capacity USB rechargeable external battery pack that helps digital and thermal devices that lasts up to 20 hr on a single charge during extended period of usage. Ideal for the nighttime hunter who doesn't want to change batteries during strands or while in field, the PB8I features a built-in charge level indicator and more than doubles the operational time of external equipment. Weapond mountable, this unit is waterproof and shockproof, allowing it to be mounted directly to a firearm or other device with a picatanny rail. This power bank will increase battery life without greatly increasing the overall weight of the firearm.