The Wolf Tooth GoatLink 10 Speed 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 Wolf Tooth GoatLink 10 Speed, created 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. Wolf Tooth GoatLink 10 Speed Compatability Compatible Shimano Shadow+ 10-speed rear derailleurs (clutch type ONLY) have a Direct Mount link (including spacer, if so equipped) or B-pivot knuckle with a thickness of 7.9-8.1mm.  Shimano changed to this sometime in 2013. Very early Shadow+ rear derailleurs have a thinner link and are not compatible.           The GoatLink is optimized for use with Wolf Tooth’s 40- and 42-tooth GCs and all sizes of Drop-Stop chainrings - but will work with any 11-40t or 11-42t 10-speed cassette.  Direct Mount-native frames and SRAM rear derailleurs are not supported.  You will never need a longer b-screw with the GoatLink Improvements with the GoatLink* Chain wrap at 11t (effects cassette life): 40t:  Improved by 69% 42t:  Improved by 53% Free chain length at 11t (effects shifting precision): 40t:  Improved by 25% 42t:  Improved by 19% *Due to variations in derailleur hanger geometry, chainstay length, chainring size, B-screw adjustment, and suspension configuration, individual results will vary slightly. Wolf Tooth GoatLink 10 Speed Specifications Weight:  19g Material:  6061 aluminum Included:  stainless steel bolt Torque:  8-10Nm Made in the USA