It's the Shimano Ultegra CS-6700 - 11-25T

Complete bike specifications
Frame: Santa Cruz V10 27.5, size large
Rear shock: Fox DHX RAD
Fork: Fox 40 Float RAD
Headset: Chris King InSet
Stem: Enve direct mount
Handlebar: Enve DH
Grips: Lizard Skins Lock-On Charger
Front brake: Shimano Saint BR-M820 w/ 203mm RT86 rotor
Rear brake: Shimano Saint BR-M820 w/ 203mm RT86 rotor
Brake levers: Shimano Saint BL-M820
Chain guide: e*thirteen LG1+ Turbo
Rear derailleur: Shimano Saint RD-M820
Shift levers: Shimano Saint SL-M820
Chain: Shimano
Crankset: Shimano Saint FD-M820, 165mm, 38T
Bottom bracket: Shimano SM-BB80
Pedals: Shimano DX PD-M647
Rims: Enve M90 Ten, 32h
Front tyre: Maxxis DHR II 3C, 27.5 x 2.4in, tubeless, clipped, 29psi
Rear tyre: Maxxis DHR II 3C, 27.5 x 2.4in, tubeless, 30-31psi
Saddle: WTB Vigo Titanium
Seatpost: Enve, 5mm offset
Other accessories: MarshGuard front fender and 'Stash', MarshGuard number plate, titanium hardware