Metallic Series rowers are equipped from the factory with key brackets with adhesive felt installed on top of the brackets. The purpose of the felt is to prevent creaking or rubbing noises in the tank assembly associated with the heavy use that Metallic Series rowers typically see in commercial gym settings.
Over time, the felts may disintegrate and require replacement. Also, Metallic Series rowers produced prior to October 2016 did not have these felts installed and doing so may be a beneficial upgrade.
Installation is simple — follow the procedure in the video below.