The video lead weights can either be inserted in the lead-belt included in some housings or strapped to the lead-belts fitted under some units. Please do not hang lead to housings that are not in the water. This will cause unnecessary wear to the housing & decrease its life expectancy. Clip the weights on as the housings reach water level. Both weights are covered in a special latex to ensure that the can not leave any marks on or scratch your camera. Please note, that the flexible housing behaves just like the organs of a diver with regards to water pressure. As stated by the law of physics of Boyle-Mariotte (pressure x volume = constant) the volume of air in the housing (just as that in the lungs, diving jacket & the air inclusions in the diving suit) decreases as it descends. In other words, a housing that is positively buoyant on the surface will be neutral at a certain depth & thereafter even show a tendency to sink. This point can be "adjusted" by adding weights to the housing, the amount of air included in the housing & some practice. These lead weights are also suitable for use with the U-A & U-B autofocus SLR housing series. Ideal also for almost all video housings.