I have these installed for the last 7 years...excellent product with no yellowing. Slight pitting at this point so I'm thinking of replacing them but will first try to polish them.

2005 BMW X5 | Headlamp Headlight Protection, LampGard by WeatherTech | WeatherTech.com

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2005 X5 4.4 (Sterling on Truffle) w/sport everything
2011 Audi S4 (Prestige, DSG)
2012 Audi Q7 (Sport, S-Line)