Neewer Compact Lightweight Portable External Battery Pack Replacement for Canon Speedlite Flash 600EX,580EXII, EX580,EX550,MR-14EX, MT-24EX, Neewer TT520,TT560,TT660II, NW565,NW985 Designed to boost the recycling speed for your flash in a much more effective and economic way. Red light indicator for working status. Smart 1/4" screw knob design for mouting the battery pack beneath your DSLR camera.Do not force the screw knob through the hole.You need to spin the screw in for the hole to hold it. No complex operation needed. Easy to use. Suitable for Canon Flash: 600EX580EXII, EX580,EX550,MR-14EX, MT-24EX and Neewer Flash: TT520,TT560,TT660II, NW565,NW985