I have a fiberglass cap on the bed of my pickup truck. when it rains or snows, or during any inclement weather, i can not see out the back window of the cap. there is no wiper for the back window.. all suv type vehicles have a wiper, but not truck caps. why? i understand that your fmvss no. 111, rear view mirrors, states that i should be able to see out the rear window, to the horizon, clearly. without a wiper that is impossible. when the caps are installed on the trucks it blocks the upper brake light, and you made the cap manufacturers put an upper rear brake light on the back of the caps. since the cap manufacturers are in violation of the rule, you should force them to install wipers on all their caps. it is a safety issue. i read on a michelin wiper blade advertisement that 40% of all accidents are caused by reduced vision. a wiper system is available on www.truckcapwiper.com.they should buy them there and install them on all caps.