19 x 18: is an extreme version too, Only for track use, not compatible with ABS.

Radial Master Cylinder Brembo PR 19x18, with Standard Lever / special IDM-Superbike:

Specifications:
-- Piston diameter 19 mm
-- Leverage translation 18 mm
-- Housing made of forged aluminum
-- Hard anodized
-- Brake Fluid DOT 4, or 5.1
-- for bolt M10x1,0 for fixing the brake hoses
-- Weight 264 grams

Available spare parts:
10459461 Standard Lever 10426660 Push rod replacement kit
10281581 handlebar clamp
10459240 lever mounting
A6500960 clip for fastening leverage
10511010 lever setting (leverage)
10510710 lever screw Leverage (outside)
A51101046 span pen for 10510710
05338760 bleeder screw
10312710 hose connection (10312720 is possible, too)