Which battery company and the voltage is the best for and APS 103 M4?

[SPAZ_REACTIONZ]

I dont know which battery is the best for my gun and i want a good well known brand that has already been tried out. I know the voltage cant be higher than 9.6 so I just need a good company becouse I dont want to get a crap one and have it brake on me while in the middle of a game. The gun is an APS 103 M4 Full Metal Blowback Rifle

 

[Deva]

www.component-shop.co.uk

They are cheap, but reliable