Universal Hot Tub Cover Lifter. The new Cover Rx (cover prescription) is compatible with virtually any above-ground spa on the market today. 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 and requires no drilling into your spa cabinet. Your spa cover is supported entirely by the Rx and does not place any unwanted stress on the center cover seam which translates to a longer cover life. ...