The GoatLink is simply the fastest route to improved wear and long-term shifting performance on wide-range 1x10 drivetrains using the Shimano Shadow+ Rear derailleurs. The GoatLink, made by Lindarets and Wolf Tooth, re-positions 10-speed Shimano Shadow+ Rear derailleurs to the optimal location when using the GC 40T and GC 42T cassette expanders.