When I bought my H.S. tub, I liked the cover on the Beachcomber models better as the 2 halves of the cover had a long insulated wedge that filled that space wall to wall. Now I have heard that H.S. sells a long attachable wedge that fills in that heat losing space in the cover. Does anyone know what this wedge costs? Also, is there much heat lost thru that space between the 2 cover halves that would make buying such an attachment a cost saving advantage?