This filter is designed to go over the lower intake in the foot well of most spas. With these filters in place you can filter out the heavier particles that fall to the bottom of the spa and do not get collected by the skimmer. WARNING: Most spas have two intakes for each pump. DO NOT COVER BOTH INTAKES TO A PUMP. If you do this and forget them they will stop the flow of water to the pump when they get dirty and this can cause damage to your system.