Are you asking style? It probably takes only one style. If you're asking size I'll give you my experience. These little devices love to fail without warning causing much heart ache. Recently I'd shot a major event, 500 photos and I was lucky. I uploaded and put the card back in my camera to format and bingo! - failure. I couldn't have replaced those photos so I was very fortunate.Given that, I only buy 4gb cards. 8 and 16 are fine but they can be expensive so... if one of mine fails I don't have a major expense replacing it - get the idea?I carry a 2, and a couple of 4's in my bag always.

The best memory card that I have found would be from Sandisk. Its the 8GB size Class 2. It's great and holds all the pictures you need it to. Good card for the money