OM617 Turbo chain rail material

[signalredcoupe]

Hi everyone, my first question on the forum. I recently bought some timing chain stuff on line from an obvious reputable supplier. The main chain rail off of the tensioner of the replacement one seems to have a very hard rubber surface instead of the hard plastic from the original in the car. The supplier told me that they change them back & forth over the years & that it's a German part & it'll be fine. Anybody out there have any info on this? Seems to me that it might be quieter than the plastic, but less durable over time. Thanks, Paul.