What does H9 in Stainless steel mean?

H value is the size tolerance. Lower value has tigher tolerances.

IZE TOLERANCE OF ISO SPECIFICATION Dia. Or Distance Across(mm)Tolerance Precisionh6 h7h8h9 h10 h113Max0 -0.0060 -0.0100 -0.0140 -0.0250 -0.0400 -0.0603--60 -0.0080 -0.0120 -0.0180 -0.0300 -0.0480 -0.0756--100 -0.0090 -0.0150 -0.0220 -0.0360 -0.0580 -0.09010--180 -0.0110 -0.0180 -0.0270 -0.0430 -0.0700 -0.11018--300 -0.0130 -0.0210 -0.0330 -0.0520 -0.0840 -0.13030--500 -0.0160 -0.0250 -0.0390 -0.0620 -0.1000 -0.16050--800 -0.0190 -0.0300 -0.0460 -0.0740 -0.1200 -0.19080--1200 -0.0220 -0.0350 -0.0540 -0.0870 -0.1400 -0.220120--1800 -0.0250 -0.0400 -0.0630 -0.1000 -0.1600 -0.250