Ski-brakes sold before autumn 2017 are NOT compatibles with the Meidjo 2.1 and 3. Ski-brakes, sold since autumn 2017 are compatible with all Meidjo models.
Meidjo 2.1 Ski brakes are compatible on Meidjo 3.
Meidjo 3 Ski brakes are compatible with Meidjo 2.1.