Cat SX2- what battery do you use?

[Maxbashing]

Hi all, there is a similar thread on here somewhere but it hasn't helped much. I have just bought a second hand Cat SX2 which came with 1 Trakpower lipo. I want to buy a few more batteries for the car but I'm struggling to find something that I am confident will fit. Can I please ask all Cat SX2 drivers what batteries do you use? Ideally I'd like something readily available in the uk so I can get them delivered soon.

Thanks for your help.

Max