Excerpt: If you are diving with your camera, this weights are definitely a must! I used 3 of them as recommended by Canon, and the neutral buoyancy was perfect. I could just let go of the camera at 50 feet and it just stayed there floating in front of me.
Pros: Easily Loaded Equipment, Strong Construction
Excerpt: With a positively buoyant camera housing like the Canon housing for my G12, the camera is a hinderance when you need your hand (camera is typically on your wrist secured by a lanyard) to do something dive related (inflating a safety sausage for instance). With the weights you can make it less positively buoyant or negatively buoyant depending on the risks and issues you expect on your dive.
Summary: I have a WP-DC22 case that suggested using 1 weight. Without the weight the case was slightly buoyant, and slightly negative with the weight. The weight helps keep the camera vertical in the water, but how many underwater subject require a vertical camera? While diving I find I hold the camera horizontal, it was more of a strain and less comfortable to hold the camera with the weight.
Summary: Used in Hawaii for the first time. Thanks to another review I was warned it was needed. Only used one weight out of 4 and the camera sank. It screws onto bottom with provided screw (no tools needed). Also comes with extra screw and weights. No weights the camera floats, so if your not using it for diving, you won't need the weights. For diving use one weight and she will sink.
Summary: Helps keep the camera heavy for when scuba diving with an underwater camera. Otherwise, you'll be chasing your camera to the surface if you let go or lose your grip. It only sets you back a few more bucks on top of the somewhat spendy casing. It's added convenience at a moderate price.
Summary: Overall, I am happy with this purchase. I used these with Canon's waterproof housing (WP-DC8) on a total of 6 dives and a couple of snorkel trips. However, I would like to make others aware of a couple of small points. You might think that there is nothing special about designing weights for a camera case, but after using these I can say there is some room for improvement.