Stair TreadsProduct Description 1) Material: Carbon steel or stainless steel 2) Bearing bar specification: 20 x 3mm to 90 x 7mm 3) Bearing bar pitch: 12. 5mm, 25mm, 30mm, 33. 5mm, 37. 5mm, 40mm, 50mm & 60mm 4) Cross bar pitch: 25, 38, 50, 50. 8, 76, 100 & 101. 6mm 5) Maximum length of black panel: 6, 100mm 6) Material: Carbon steel or stainless steel 7) Surface treatment: Untreated, paint or hot dip galvanized 8) Steel grating standards: A) China: YB/T4001-1998 B) USA: ANSI/NAAMM (MBG531-88)