They were about £13 each. Goes on front of the frame in the interior mounted with velcro straps and has a zip in the middle to unzip and open/close the window. Keeps the flies and moths out thankfully.
Although Ironically, I found a small spider camped on my net catching the bugs who get stuck on it! Lazy bug-ger can’t build his own web! But I left him be.
It’s an absolute lifesaver- beforehand I’d hate opening the window due to the insects. My bedroom would get extremely warm. Now I can vent air out and not worry about critters.
That was one of the hardest things to adjust to, moving to England. Where I’m from, screens on windows and doors are extremely common for this reason. Once we have a place of our own, we’re definitely getting them installed. We like the breeze.