This product makes the correct masking of rubber seals around windows etc. so much easier, enabling the rubber to be folded away from the bodywork slightly avoiding a hard paint edge and the possibility of peeling. There are two plastic edges attached to the tape, the outer one being 8mm and the inner one 12mm. This is good if the rubber seal only has a shallow flange. The tape itself is perforated at 40mm intervals, making it easier to deal with corners, although it can of course be cut if required. Hopefully the attached picture clarifies my explanation.