It is 6 mil film, I bought it back in 2017 but I keep using it for these temporary hoops. They are not fancy by any means, but with all day sun I will have beets, lettuce, carrots, radishes, spinach, and onions sprouting by the first week of March. If there is a really cold stretch I can just cover with last year's leaves for a few days.
If the snow is too heavy, I will need to remove it. If they were permanent structures, I would add a support down the center and decrease the spacing between the hoops to increase strength. I use pvc brackets to connect to the hoops, they give fairly easy, but that is ok, it actually protects from ripping the film.