The mini-factory car windshield cover says it is for snow, ice and sun. Thankfully I haven't had any snow or ice this season to actually fully test this BUT I will update...I put it on my Explorer every single night just in case. It is really easy and FITS my Ford Explorer.
The fit is perfect. Originally I was concerned that the door would not fully close BUT it does. The piece covers my entire windshield with enough room on both flaps to be closed inside the car. It is kept in place by the closing of the doors. It has been windy here and I thought I would lose it the very first night I used it. So far. So good. It doesn't shift at all. It is easier for me to have help when using as I am short and my windshield is really high and wide for me.
I would purchase again, in fact, I am getting one for my husband. Much easier than getting out of work after a 12 hour day to chip ice off your windshield so you can drive home.