batteries for GMP?

[nellyt5]

hi guys
sorry to have to ask this AGAIN
but now i have read almost every thread on batteries,im now even more confused
the 2 DIFFERENT sets of 4 re-chargables in my gmp were in it when i bought it 2 years ago,never had any probs tho
but i thought it was about time i changed them for piece of mind,
so 2 questions ;
1 which ones do i buy,
2 will the 1.2v have any detremental [ dont look right ] effect over the 1.5v
thanks in advance

[nellyt5]

sorry guys
didnt notice the post below
my bad