Appraisal:
* The quality of the plastic film is similar, or even greater than that of the ready-cartridges therefore no risk of the drill while we try to stick a layer.
* Easy to apply as long as we keep the diagram provided in product photos by Amazon. Only problem: after a while, it's hard to get the film right inside by stuffing. The amount of film used takes into hardly a week (20-30 layers); beyond, reload.
So it's a purchase I will do it again when I have exhausted my stock.