I had to get new battery for the transmitter of my 'Yongnuo' flash trigger outfit -- it was a '25 A 12 Volt' type. There are MANY Yongnuo outfits according to what camera you have and if you want 'TTL Flash Metering' and so on. I just got the one that had a plug for 'studio flashes' as shown -- I did a VIDEO about my outfit which you can see.