It is something you feed your dog, but if your talkin about dogbone inserts for your golf, the dogbone mount is a link which attaches the engine to the chassis, the insert your talking about removes some of the flex in the mount. Milltek recommend it when fitting a large bore downpipe, it also sharpens throttle response by removing some of the intial engine movement, it can increase a little vibration into the cabin, but I've haven't noticed any in the last 3 cars I've fitted the insert on
