This abrasive sandblasting media tool will help you calculate grit to micron conversion. Also, there is a grit to micron chart, and conversions for mesh.
Sandblasting Media Guide, Sand Blaster Media
SA 2.5 or SA 2.1/2 & SA 3 Shot Blasting, Grit Blasting Comparators – Testing, Inspection & Measuring Instruments Dealers in Kolkata, India
Sodium Bicarbonate Sandblasting Media 50-100 Micron (120-220 Grit
GMA SpeedBlast Garnet Abrasive Media for Sandblasting
Sandblasting Grit Size, Microns, Mesh, Inches Conversion Chart
Aluminum Oxide ALOX #150 - 12 lb Interactivia Blast and Tumble Finishing Media
Walnut Shell Sandblasting Media 20/40 Grit - 50 lbs. - 97931 - Vaniman
ProBlast Micro-Abrasive Blasting system.
Aluminum Oxide Sandblasting Media 50 Micron (240 Grit) - 15lbs