The window regulator is the component inside of your door that actually makes your window go up or down. The regulator consists of several moving parts that work together to lift or lower your window. As with anything these moving parts eventually wear out and need to be replaced. If you have noticed increased resistance when rolling your windows up or down, you might want to look into a replacement regulator. Look to Trucktec window regulators for a great part at a great price.
OEM: 210 730 16 46, Item: 493795
OEM: 210 730 15 46, Item: 493793
OEM: 210 720 00 42, Item: 531812