The Gen 4 X1 PRO fits all standard and fat bike bottom brackets from 68mm to 120mm. It has a special BB92 Version which has a spot on chainline. BB92 Pressfit frame is common in modern mountain bike frame. It is typically very difficult to convert BB92 bike into electric due to the offset chainline. The BB92 is designed to be direct fit and with a perfect chainline of 51mm.
X1 PRO comes with a Torque sensor that is used in pedal assist mode. The torque sensor measures how hard and cadence measures how fast you pedal. These are collected and processed together by the controller to provide natural feeling of pedal assist and calculates how much power the motor should output correspondingly. A big bonus is that it also measures and records your own power via the mobile app so you can monitor your exercise rate. You can also customize the proportion of the motor power output in case you want to change the ratio of assist. EMTB mode when using comparable power levels.