Rule of thumb is, if you can't see it - it's fine. [

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Technology has developed and improved this product over the last few years.
The latest, high-end films promise to last up to 10 years - remains to be seen, of course. [8|]
Older or inferior films tend to discolour or peel and eventually become unsightly.
All films tag from stone damage and the film self-heating properties are overstated by the manufacturers IMHO. Over time, damaged film surfaces, stretching, lifting and fingering at panel edges/joints tend to lead to the need for replacement, but this depends on how well the film was applied originally and your vehicle usage.
Removal is best left to an expert - particularly if the headlights have been done as these have a thin lens coating, easily stripped off by removing the film.
Coachwork damage will be double the cost of normal repair due to the need to also replace the film.
Regards,
[font="comic sans ms,sans-serif"]Clive[/font]