Cover Valet™ CV250 Premium Undermount Hot Tub Cover Lifter for Spas Under 95". The Cover Rx is just the prescription for virtually any above-ground spa on the market today. It is ideal for roto-molded and soft-sided tubs, where drilling into the spa cabinet is not an option. The unique undermount installation plate allows the Rx to be installed on whatever side of your spa you choose and requires only 18″ of clearance. Whether your spa is square, rectangular, octagonal, or round the Cover Rx will be a perfect fit. Your spa cover is supported entirely by the Rx, keeping it off the ground and reducing wear and tear. There has never before been a more complete spa cover lift.