I have no clue what grit equivalency mine is, but it gives a damn good shave. Like a hot knife through soft butter. Mine is also 10x2.5 which is mad nice cus you have a lot of area to work with....

The guy I bought mine from seems to know a lot about them. He is of the opinion that the "pear" coloured ones are the finest. Ie the yellowy ones. Mine is a beautiful swirly mix thats mostly yellowish but has soem olive hues and baby bluish areas.