This is a basic hydraulic disc brake available in three sizes of disc: 160, 185 and 203mm.
With a split clamp on the lever, fitting couldn't be easier, and changing brake pads is as simple as pulling the old ones out and popping new ones in. It gives great progressive feel and isn't snatchy or too grabby in use, even when really hot.
Performance in the pouring rain is exactly the same feel as in the dry - smooth and progressive with plenty of power in reserve. Fitting is easy too - all you have to do is keep the floating mount bolts slightly loose, pull the brake on nice and hard, and then tighten the bolts up.