The lid Size: 163x36mm,as the pictures shown. Excellent IBC tank part, especially if you need to drill out for down spout or bulk head fittinp! IBC tank lid is made of high density polyethylene,can also provide chemical resistance IBC Tank Lids Water Liquid Storage Plastic Cover Lid Cap Adaptor with Gasket for Chemical Medicine Food and Other Industries Package Contents:1 Pc x Tote Tank Cover Lid + 1 Pc x Gasket. The lid suit for IBC tank diameter 163mm/6.42inch