CornerSealer is a practical pen-shaped device, the tip of which heats up in 10 seconds, which makes it useful for fixing the film at the edges and corners. To avoid overheating, it is enough to keep the tip on the film for a few seconds and you're done! It is important that the device is not switched on for more than 5 minutes! It works with 2 AA batteries, which are not included in the package.