Normally sold as a caravan skylight cover but just as suited to protecting your windscreen from UV, frost or the glare of the sun when parked up.
 
Ideal for most vans. Measurements are 220cm wide and 90cm deep, simply shut the straps in the hinge of the doors. Waterproof and breathable with a super soft layer to go against your screen.
A really cost effective alternative to other expensive options or an inadequate tarpaulin!
 
We use it all the time on our motorhome :)