Battery 4 (QB4) (12v) Similar to other Quantum batteries in appearance, the QB4 is designed for use with 12 volt flash units such as the Nikon SB11, Rollei E36RE and Agfatronic 643. Offers over 250 full power flashes and up to 1000 flashes and more when using the flash in auto or TTL modes. LED displays: Power monitor "fuel gauge", on/off, short circuit, and recharging indicators. Twin output jacks - allows two flashes to be powered together. Dimensions: 8x3x1.75 in. Weight: 40 oz. Accessories include: Replacement Charger 110/120 VAC (QB28), 10 ft. Module Extension Cord (QB23), European Charger 220/240VAC (QB31), European/Scandinavian Charger 220/240 VAC (QB39), Battery Mounting Clamp (QBC). As with all Quantum batteries, the QB4 has the sealed "no memory" lead cell rechargeable battery, which will give over 100,000 flashes over it's lifetime. Can be fully recharged at any time no matter how much charge it has. The pack holds it charge for months when not in use. The lead cell can be replaced if necessary.