Should my IronRidge Stopper Sleeve be the same size as my solar panel, or a few millimeters shorter? Posted by John, IronRidge on Apr 8th 2019 You should select the same size IronRidge Stopper Sleeve as your solar panel. For example, if you have a 46mm tall solar panel, you would select the 46mm size stopper sleeve. IronRidge Stopper Sleeve UFO-STP UFO-STP-46MM-B