G737PB is a portable charger that can be used with the G737 offender tracking device. This GPS tracker power bank is designed to offer ease for the user so that they don't have to sit for a longer time to charge the battery with a wall charger. Now they can just clip the portable charge on the offender tracker and walk around. The power bank with GPS tracker can charge the G737 ankle tracker bracelet fully in 2 and half hours.