SWIT KA-B21S, V-MOUNT BATTERY PLATE FOR B-MOUNT DEVICES/CAMERAS, 28.8V, HIGH LOADV mount to B mount Conversion KA B21S conversion plate allows you to adapt V mount batteries to the cameras with B mount plate, like ARRI ALEXA 35, Blackmagicdesign URSA CINE. KA B21S doesn t change battery voltage. The B mount side outputs the same voltage of V mount batteries. 28. 8V Battery to Power ALEXA35 SWIT Bi voltage V mount battery recommended Use SWIT PB H290S 14. 4V 28. 8V Bi voltage V mount battery, the KA B21S plate will active 28. 8V