The Cover Guy receives this question a lot so we thought we would explain what we mean by taper. A hot tub cover is built like the roof on your house, it has a pitch, taper, or as some refer to it a slope. The idea of taper is that rain, snow, and debris will roll off your hot tub cover because of the taper or slope used on your hot tub cover. So, the taper on your hot tub cover refers to the slope of your hot tub cover.
For example, 4 to 3″ means the hot tub cover is 4 inches thick in the middle and tapers to 3 inches at the end. This is a gradual slope, or angle that looks like the pitch on the roof of your house. This taper on your spa cover allows water to run off.