Which batteries for my Mp5's and M15a4?

[FredFunk]

HI one and all

I have a Classic Army Metal Body M15a4 and Marui Mp5 kurtz and a Mp5 Sd5 for sale, (all have been battle tested at Dragon Valley!) Which batteries do you guys recommend as their original batteries dont really hold a charge so I'd like to replace them with something decent but not too expensive as I may have to add that extra cost to the sale price. I didn't buy the guns new but I'm assuming that they are stock. The Classic Army and Sd5 came with(and shared) the battery shown below. The Kurtz's stick battery dosent want to come out and is putting up fierce resistance.

I've seen a few batteries on ebay but thought I'd see what advice the forums could give me.



Regards Fred