Been looking at these at the local Discount Auto Parts, they come from the manufacturer set at a certain pressure (32lbs and 36lbs). You screw them onto your tires valve stem and, if the pressure drops below the setting a little red ring becomes visible. There is a green ring that is visible if pressure is above the setting. Well, been looking at them for a couple of weeks but couldn't get around the "cheesy" factor. Finally bought me a set of the "36", I run 36 in the front and 40 in the rear. Installed them and, lo and behold, my rear tire was low (31). Fired up the compressor, filled the tire. I know, it sounds cheesy but they really don't look bad. I suspect most people won't even notice them as they are mostly hidden by the brake rotors. Anyway, I know they ain't chrome and ain't from Harley but they do seem to make it ez to check the tire pressure.