The tronix external power supply speedfire ii for nikon speedlites is an external power source, so you'll never have to wait to recharge your flash again! Plus, you can avoid having to suddenly change your batteries during an important shoot. the tronix speedfire ii powers your camera flash and has an impressive charging time of just 0.02 to 0.5 seconds (depending on the brand and set output of the flash). this allows you to continuously fire your flash. the speedfire ii is mainly intended for use in a studio or at home. The speedfire ii is a portable and easy-to-install external power supply designed specifically for nikon camera flash units. all necessary cables, batteries and other accessories are included as standard. the power supply itself is equipped with velcro, so you can easily and securely attach it to any object. for high reliability, the device is equipped with an auto-cool-down function. this will automatically turn off the unit if it gets too hot. The speedfire ii for nikon is in any case compatible with the following flash units: sb900, sb800, sb80dx, sb28dx, sb28, sb27, sb26, sb25, sb24, sb20, sb11 en sb22. do you have a canon flash? Check out the canon speedfire ii with the optional accessories. Usage tronix external power supply speedfire ii for nikon speedlites To use the external power supply, plug the connector cable into the dc output of the speedfire and connect it to your nikon camera flash. then connect the speedfire to the mains using the included mains cable. now the unit will start automatically and the red led on the speedfire will light up. then connect the cable, to which both dummy batteries are connected, to the dc-input at the top of the speedfire. the batteries themselves are placed in the battery compartment of your camera flash.