What batteries to use?

[LiL Miss DeL ReY Vape]

Hi this is probably going to sound stupid so I apologise in advance,but if anyone has the innokin 134 mini, what batteries do you use for both the extender peice that makes it compact and the normal size because I've heard a couple of different sizes one site says 18350+ 18470 and another site says 18350 +18500, so I'm confused as which to buy? Thanks