It is a well-known issue on the N54/N55/S55 platforms that your serpentine belt can fail for various reasons, when this happens you have a high chance of the belt getting sucked behind the front damper, and then being pushed past the crank seal into your oil pan. From there it can get sucked into the oil pick up causing total engine failure, even if you do not lose the engine it is a COSTLY repair to remove the sub-frame and drop the oil pan to remove the belt. The best way to combat this is to watch for oil leaks and keep up on your maintenance. BUT Even with those preventative measures, pre-mature belt failure can occur. This crank seal guard installs over your front crank seal and will keep the belt from being sucked in if a belt failure does occur. This is a cheap way to ensure you do not end up having to replace your motor from oil starvation due to an ingested belt.