Treats? Bananas and raisins?

So I just got two chinchillas two weeks ago from a girl on kijiji. She was giving them bananas and raisins as treats, however I have been learning that she really did not know much about chinchillas... So I am wondering if giving them 2 banana chips a week, and 2 raisins is too much? Or if these are even okay treats to give?

Thanks!
Christina