Nightstick CR-123 Backup Battery Holder for TAC-500/550 Series LED Lights Black. If the rechargeable battery on the TAC-500 series light were to be depleted the user can insert a pair of CR-123 Lithium batteries into the carrier and then use it in place of the rechargeable battery. Requires 2 - CR-123 Batteries which are not included. Not compatible with TAC-400 Series. Specifications for Nightstick CR-123 Backup Battery Holder: Manufacturer: Nightstick Color: Black Battery Type: CR123 Bulb Type: LED Features of Nightstick CR-123 Backup Battery Holder: Fits the TAC-500 series Back-up lithium CR-123 battery pack (batteries not included) Adapts TAC-500 series to CR-123 battery power Backup power when the rechargeable battery pack is spent Package Contents: Nightstick CR-123 Backup Battery Holder Nightstick 500-CARRIER: CR-123 Backup Battery Holder for TAC-500/550 Series LED LightsBlack