Differential protection is pretty much an accepted thing in the off-road world, everyone needs some. All covers come with a lifetime guarantee, no questions asked.Everything is Cad designed, CNC Laser cut, and bent on a CNC Brake (290 Ton). It is a 1 piece Plate steel cover bent 8 ways, way hard to hurt in .375 (3/8"). The ring is also .375. The fill plug is a generous 1" ID for easy fill and oil level check. One of the reasons it is so hard to hurt is that we manufacture it out of A50 Plate Steel, thats 50,000 PSI Tensile strength. This is for a fully welded D30 High or Low pinion Cover, welded inside and out. All welds are made by a competent & certified welder in the US from US manufactured Steel. Covers are shipped in bare steel for you to customize.