M16 stock battery size?

ok so my batteries I've been using get stuck in my stock, I'de like a actual large battery but not sure of size,
http://www.airsoftgi.com/product_info.php?cPath=27_47&products_id=3355
would this fit??

of its an M16 A2/3/4 stock it should...

think it'll fit in a E1 PEQ box also?

No, those use special batteries (I think). But don't trust me on battery info, haha.

It wont fit in an Peq,

Like mgunner564 said, it should fit, I use the same Battery in mine, it´s a bit tight, but fits without a problem.

okie doke! how long should it last? im thinking about picking up two of em and another nunchuck (last one wire ripped out in the field, not a good thing )

Depends on how you play, if you are blasting the bejeezes out of everything, they are going to be empty after about a half day of playing. I´ve gone entire weekends on just 1 Battery.