SRAM Red 1X Power Meter Crankset E1Power meter is fully integrated into the chainring for lighter weight and greater accuracy Power readings are accurate within + 1. 5% and arent affected by climate conditions during a ride Measures right and left leg power balance Ultra light hollow carbon fiber crankarms are 29 g lighter than previous generation DUB bottom bracket adds durability and simplicity Available in 160, 165, 167. 5, 170, 172. 5, and 175 mm lengths