JJC FB-1 External Flash Battery Pack for Canon 600EX-RT 580EX 580EX II 550EX 540EZ MR-14EX MT-24EX YONGNUO YN-560IIISpeedlite Flash Units The pack can be loaded with 8 AA-size batteries - alkaline, lithium, or Ni-MH Total minimum flash recycling time can be as fast as 1seconds when used with AA Ni-MH batteries. JJC FB-1(II) replaces CANON CP-E4. Compatible with: Canon 600EX-RT, YONGNUO YN-560III, 580 EX II, 580 EX, 550 EX, MR-14EX, MT-24EX. One (1) External Flash Battery Pack (batteries not included), One (1) Carrying case