Description Protective Design----Included protect case which available to hold on the belt or bag; easy to carry.It's also much increased the protection .The connecting plug anti-wrong inserts desinged; avoid missed using to failure flashlight system. There included the screw which can hold on the tripod mount. Performance --- Through the best ,the external battery pack can be able to reduce the recycling time. The recycling times of flash as original. It is very suitableto use in continuous flash. Much useful --- This product need to insert the 6 new AA batteries (Same battery type as the flash unit) through difference connecting plug, support to use Canon flash light, and greatly to increase the flash light working ability .This is the best for the professional person