We found this invention on the Web. Moshammer released its hydraulic brakes for skates in 2010. Il s'appuie sur l'énergie hydraulique. Two cylinders slow down the wheels. German components seems good... but the price is incredible: over €400!
Only available with the following models: Rollerblade Speedmachine / Tempest / Powerblade, K2 Radical, Fila.
More info: Moshammer