This product is designed for the traditional 20 mm rear axle setup of Beta motorcycles. The most current compatibility status, including up to the 2026 model year, is as follows:
 
✅ Compatible Models (Using 20 mm Axles):
 
Beta Xtrainer (250/300): 2015 – 2026 (Fits all years seamlessly)
Beta RR, RR-S, and RR X-Pro: 2010 – 2026 (The standard series continue to use the 20 mm axle)
Beta RR Race Edition: 2013 – 2024 (Fits only up to the 2024 model year)
 
❌ INCOMPATIBLE Models (Transitioned to 22 mm Axles):
 
Beta RR Race Edition (2025 – 2027): Because Beta increased the rear axle diameter to 22 mm for its Race-equipped models starting in 2025, this nut does not fit the new generation Race models.
Beta RX Series (Motocross): The RX series comes standard with a 22 mm rear axle, making it incompatible with this nut.
In short, as long as your motorcycle's rear axle diameter is 20 mm (which applies to standard RRs and Xtrainers), you can safely use this part, including on current 2026 models.