The white funnels (stop buffer for deflection) it is installed on the mount prior to assembly on the subframe, (it has the same shape as the inner side of the mount) with the narrow end pointing downwards to go through the hole on the subframe cup. It was a MB revision for the subframe mounts to prevent the aluminium core to rub against the hole on the subframe, originally it was not installed. It applies to all 107, 114 and 115 models.
Could you elaborate on
"My car drives very rough now when I accelerate"?
