Shimano Ultegra ST-8150 Di2 Dual Control Shift/Brake Lever for Rim Brakes - Left, 2x, Black headsets They're scientifically tested to help

They're scientifically tested to help reduce hand numbness by improving circulation and equalizing pressure in the soft tissues of the hand

Spring: 8 to 12

explosive acceleration

If you had to choose just one wheel for road riding and racing

LifeLine™ palm construction eliminates bunching

Shimano Ultegra ST-8150 Di2 Dual Control Shift/Brake Lever for Rim Brakes - Left, 2x, Black headsets They're scientifically tested to helpShimano Ultegra ST R8150 levers combine the accuracy of Shimano 12 speed Di2 shifting with the light weight of rim brakes. Quick and intuitive shifting Clearly defined click feeling with ergonomic shifting lever Better bike control and confidence in race conditions Hood shape and texture optimize grip and brake power transmission