Honestly, they are not worth the money.
I picked mine up years ago from Scandinavian Outdoors Store.
The quality and method of construction is poor. Eyelets punched through seams and stiches.
My missus, a Garment Technologist, rolls her eyes whenever she sees it. She can't bare to look at the shoddy workmanship.
It was however my first tarp after graduating from Basha and Ponchos. So I love it for that. When it finally falls to bits, I'll get something different.
The level of quality of reflection is also significantly worse than mylar or similar products, such as SOL's utility blanket.
Really, if you are wanting to escape the sun, Sunsafe/UPF50+ fabrics are the buzzwords you want to be looking at.
A bright colour, yellow, orange or even white, would also make more sense than greens or something similarly dark.