Quad are a UK-based company making a selection of quality hubs, disc and rim brakes in Taiwan. The QHD-1 is their most expensive brake but it only costs about the same as most other companies' cheapest models. They also make a QMD-5 mechanical disc calliper, similar to the popular Avid BB7 but lighter and a fair bit cheaper at £39.99.
Build quality is good, set-up is easy, the pads are self-adjusting, you can fit the two-bolt levers either way up and lever reach adjustment and pad swaps isn't particularly taxing. Lever feel is excellent too, bleeding is straightforward and the brakes look pretty good. All rotor sizes and frame fittings are available too. As for weight, the front brake weighs 375g and the rear is 390g (both without rotors). We'll report on durability after another couple of months' use.