That's what I've been trying to find without any success. The stock Brembo Master is 12 mm. There's a company Midwest Mountain Engineering that builds a replacement Brembo master cylinder for KTM's and other enduro bikes which reduces clutch pull 50% But I sent them a pic of my bike and they said their unit wouldn't work. Also I've searched parts catalogs for slave cylinders on other models (Brevas, Griso, etc.) and they all appear to be the same unit.