We suggest a 2 year guarantee to your customers. You may decide to prorate your warranty.

We like to make sure all technicians know the truth about UV sealers.
The best performance from UV sealers would be the factory
original on a new lens because it was applied to the new
polycarnonate lens that has had no effects from the outside
elements. Many systems claim a guarantee for a specific
time, however the truth is much depends upon the car owner.
Many things effect the longevity of the UV sealer, including
the factory sealer, such as recyled water at car washes,
chemicals ( dressings, engine or wheel cleaner, etc.), climate,
use of waxes, etc.. This is why you will see two cars of the
same model and year where one has crystal clear headlights
and the other with severe corrosion.We suggest you offer
your warranty with the condition that your customer regularly
applies a wax or paint sealant to there restored lenses at
least twice a year. They should apply wax a week after your
restoration. If they do this they will have clear lenses years
to come.