M14x, which R revision?

Hi,

I want to replace my battery, but I don't know exactly what is the model of my laptop! Is it R1, R2, or R3

My laptop was deployed in July, 2013 with the following information

P30G001 , Windows 8, 64 bit

intel core i7-4700MQ 2.4ghz

16 GB RAM

nvidia geforce gtx 750m with 1gb GDDR5

Thank you so much