The Canon Speedlite 177A is a powerful, compact automatic flash unit with energy-saving thyristor circuitry. Guide Number: 82. Recycling Time: 8 seconds w/Alkaline-Manganese batteries 6 seconds with NiCd batteries. Flash coverage: 35mm. Number of flashes: 200 or more with Alkalines and 70 or more with NiCds. For use with A series and the Power Winder A.