... ,drange pit cover,stair tread,ect.2.Serrated:Better non-skid property & safety compared with plain grating.3.I-shape:Lighter ... U Untreated 5..Material:aluminum plate,thin low carbon steel plate,stainless steel plate,AL-Mg alloy plate,copper plate,nickel plate.The most popular specification ... with the standed of YB/T4001.1-2007. steel grating plate