No, not the 3M window film kits - but it's the same idea/concept. It's a piece of plastic that's about 1 cm thick that's the size of each glass pane. Recently found out that it's attached using magnetic tape so i can actually them off - but the previous owners screwed in the window latches/hardware through it! It doesn't look very nice- which is what I meant by 'cheap', not actually sure how cheap it is..
Those 3M films seem like a good idea, but the year I tried them I had to repaint all the window frames as they didn't come off well. They also sag daily and need maintenance. Really not worth the bother.
I then put in the 3mm thick plastic frames which were "magnetically attached", but in practice screwed in otherwise they slip off the larger windows over time. They work well, but ugly.
I then put in proper double glazing. Works great, looks best, but acoustically louder than the second option. With PVC double glazing the window glass unit sits on spacers so that any water can run out, so all that's keeping noise out of the room around the edges of the glass is two thin pieces of PVC. With the old retrofit we had inch thick wooden frames. So it's warmer, less drafts, looks better, but we get more outside noise.