"Metalized film" insulation: anyone tried it?

[Frenchguy]

Hi,
I paid a visit to some hardware stores and i saw that insulation rolls.
It's a little thick and soft, ~ 2cm but i don't know what is inside. It's coverd by aluminium sheet but it's not heat reflectors. Sizes are 0.60 x 4 m.

Does anyone tried this product to insulate roof or wall? Does it works well to keep the house cool?