The interfit s1 is an affordable 500ws acdc powered monolight with high speed sync and ttl for canon and nikon cameras the head is powered by a high capacity 4500mah li ion battery which provides up to 350 full power flashes in manual and ttl modes and over 400 full power flashes in high speed sync hss mode firmware updates now available here httpinterfitphotographiccoms1 firmware updates