... good water permeability. We can fabricate according to customers sizes.Stair Tread Specification1. Forge Welded Grating Standardizations: CountriesNational Standards for GratingMaterialsGalvanizing ... x3/16",2"x1/4".3. Stair tread Bearing Bar Pitches:12.5mm,15mm,24mm,25mm,30mm,30.16mm(1-3/16 ... "),32.5mm,34.33mm,35.33mm,38mm,40mm,41.25mm,50mm,60mm4. Stair tread Cross Bar Pitches: 38.1mm, 50mm, 75mm, and ...