I found on that is available in the UK
The flat ones wont work well because there is no air getting to the coal. For the coal to get red hot, it needs oxygen. On of these will let it get air underneath it, cooking it faster and more thoroughly. Also, the surface area of the heating element touching the coal is nil, so there may be a spec of black on it once the coal is lit, but the heat from the rest of the coal will turn it red once its exposed to oxygen.