metal box:
material: iron
size:3"x3",2"x4", 4"x4"
thickness:0.5mm,0.7mm,1.0mm.1.2mm,etc

metal box:
material: iron
size:3"x3",2"x4", 4"x4"
thickness:0.5mm,0.7mm,1.0mm.1.2mm,etc

others:with earth screw or not, different holes.

and also many others types.