Each model of Contour camera has a specific waterproof case that they work with. If you get the wrong case, then the camera may not fit, may be too loose in the case, or may get stuck. In addition, using the wrong case will also likely cause the power and record buttons to work incorrectly.
You can see which camera the case is designed for by checking the closing latch.
**Please note that the Contour 4K, and the Contour ROAM3 cameras do not have a waterproof housing.