... water permeability. We can fabricate according to customers sizes.Stair Tread Specification1. Forge Welded Grating Standardizations: CountriesNational Standards for ... (A36)ASTM(A123)BritainBS4592-1995BS4360(43A )BS729AustraliaAS1657-1992AS3679AS16502. Stair tread Bearing Bar Sizes: 1"x1/8",1-1/4 ... .33mm,35.33mm,38mm,40mm,41.25mm,50mm,60mm4. Stair tread Cross Bar Pitches: 38.1mm, 50mm, 75mm, and ...