101K and never had a problem. Not even slow raising. Probably put silicon on the rails around 10K, but haven't touched them since. What's the key? I've probably used my drivers window 2 dozen times and the passenger window 4 or 5 times. And my VX is garaged day and night. The material in the rails is not subjected to the elements. Even my cladding is as dark as the day I bought it.