When you have surgery, a cast, cut or you are a cancer patient with appliances, you can't let the site/area get wet. The hospital will give you something similar to plastic wrap to place over your area to keep dry, but the plastic wrap is not waterproof and does not stick very well and water still gets in. If you are at home, you have to be careful not to get the area wet and may use a plastic bag or not be able to wash around the area. When you use Glad Press N Seal and medical tape to cover/wrap the area you want to keep dry while you are showering or bathing (just a note you still can't completely submerge the wrapped area under water in the bath). This will save Patients, Hospitals and Insurance Companies time and monies by keeping the area dry, clean and less chance for infection. Being a Cancer Patient and a daily user of Glad Press N Seal for the past 3 months on my own appliances, surgical areas and have had no water leak into the Press N Seal and no infection(s).