SRAM RED AXS 1x Aero Power Meter 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 SRAM Model ID: FC RED 1P E1 Attributes BB Inclusion No BCD Direct Mount SRAM 8 Bolt