Let us introduce copper wire mesh size, 6 mesh indicates that in one inch there are 6 openings. You could easily pass a pencil through the openings.
10 mesh indicates that in one inch there are 10 openings. It is used in Gutter guard mesh,ventilation screen. 
22 mesh indicates that in one inch there are 22 openings. This mesh is used in a EMI & RFI shieldong screens.
100 mesh indicates that in one inch there are 100 openings and it is used in oil filters.
