Windshield sun shades
Windshield sun shades (also known as sun screen shades, sunscreens, car shades, sun shields, heat shields, or UV shields) are protective shields attached to a car's windshield to keep the sun from reaching the interior and help reduce the temperature inside it.
The interior of a closed car parked in a non-shaded spot exposed to extensive sunlight can sustain sun and heat damage. Sunlight passing through the car's windshield produces the greenhouse effect, heating the interior to a temperature much higher than the outside air. Excessive heat and prolonged exposure to direct sunlight can make the dashboard fade and eventually crack, cause seat upholstery discoloration and aging, etc.
The windshield glass itself blocks most of the UV light and some of the infrared radiation. But it can't protect from the visible light that mostly penetrates through it and gets absorbed by the objects inside the car. The visible light that passes into the interior through the windshield is converted into the infrared light which, in its turn, is blocked by the glass and gets trapped inside, heating up the interior. Windshield sun shades have a reflective surface to bounce the light back, reducing the interior temperature
Typically, sun shields look like aluminum foil that covers the inside of a windshield to reflect the sun's rays. But today the automotive aftermarket offers various options, from simple car shades manufactured from high-density foam with a reflective metalized polyester film to automatic sun shades operated using a remote control.
Removable windshield sun shades are popular thanks to ease of installation and storage as well as an affordable price.
They are available in many designs, including accordion fold, roll up, etc. There are also permanently installed sun shades built directly into the window frame. Some vehicles can be equipped with power sun shades that move up and down with a touch of a button. Some retractable sun shades are attached with an adhesive, suction cups, etc. and roll up on the top or fold at the sides of the windshield. Some car shades are designed for winter use and attach to the outside of the windshield (typically with straps) to keep it snow- and ice-free.
A number of companies manufacture car shades, either universal or custom patterned for a precise fit. Covercraft offers easy to use sunscreens in a number of colors and patterns. WeatherTech provides vehicle-specific windshield sun shades that protect both from UV rays in the summer and snow and frost buildup in the winter thanks to reflective surface on the front side and the reverse black side that absorbs the heat in the winter. Coverking manufactures both sun shields and frost shields for summer and winter use respectively.