True, flat surface and being 10mm thick it does not flex in use. Bought for sharpening and flattening the backs of chisels and hand plane irons and happy that the continuous surface was a good choice for this purpose and the 200mm x 75mm suface is ideal for plane irons. This D8F is the ‘fine’ 600 grit version but the range also includes an ‘extra fine 1200 grit and an ‘extra extra fine’ 8000 grit model – if on a tight budget perhaps consider one of these Dia-Sharp stones for the finishing edge and cheaper (possibly double-sided) stones for lower grits to make up a sharpening set.
There does appear to be a wear-in period during which the roughness of the surface reduces noticeably to the touch, however since then I have not found any deterioration in its ability to cut and expect it to last many years.
Good value, delivered promptly and works well to clean up grindstone clogged with rust embedded debris.
Grinding wheel now feels sharp again, clean and is level for sharpening chisels.