I need to vacuum the pool's tanning ledge but because it's so shallow the regular vacuum heads don't work. The hose is connected from the top and when that is out of the water air gets in breaking the vacuum. This head connects to the vacuum hose at a right angle so the hose stays underwater the whole time.make sure to glue some felt cloth to the edges to avoid damage to the pool plaster. With the vacuum underwater the head will get sucked pretty hard against the surfaces and could scratch them.