Grinder 1a 2Human Grade Grinder 1A (2") Aluminium Herb Grinder The Human Grade Grinder 1A is a solid, no nonsense 2 inch aluminium grinder built for everyday use. Compact enough to slip into a pocket, it delivers a consistent, even grind every time. After testing it alongside several grinders in this price bracket, we found the diamond cut teeth make short work of dry herb without clogging or jamming. Human Grade has built a reputation for producing