The BG-E6 Battery Grip fits only the Canon 5D Mark II Digital Camera. It is a very nice grip in that it allows you to get double the battery life out of your camera by holding two lithium ion battteries. It also gives you two different options to power up your camera, either through lithium ion batteries or six AA batteries.
The battery grip is portable and easy to carry with you. Also, it fits on the bottom of the camera very easily, and is sturdy as well. My husband has used it a number of times already on his new Canon Mark II and he really likes it. I've tried it also and do like it myself. This battery grip is rather expensive but well worth the price. After all, it is an accessory to a camera which in itself is rather expensive.
If you are investing in a really good camera like the Canon 5D Mark II, you need a battery grip that will be able to keep pace with it, and that definitely is the BG-E6. It even looks nice on the bottom of the camera, and helps you to grip the camera better when you are holding it. An all-around great grip.