Derailleur Hanger fit for Trek Boone Crockett Domane Emonda Lexa Speed Concept 176 Black bee With the built-in laser

With the built-in laser

50 Feet Long Telephone Extension Cord Phone Cable Line Wire

Factory calibrated

Mounts to cut holes about 15

Derailleur Hanger fit for Trek Boone Crockett Domane Emonda Lexa Speed Concept 176 Black bee With the built-in laserDerailleur Hanger fit for Trek Boone Crockett Domane Emonda Lexa Speed Concept 176 Black Read more : Derailleur hanger is a metal extension of the rear dropout through which a rear derailleur is mounted. If the rear derailleur is damaged, mostly likely the derailleur hanger could be damaged as well and has to be replaced. It's also recommended to carry a spare derailleur hanger when riding a mountain bike. Below is a reference of compatibility list.