5 ply self box
A “5 ply self box” is likely a type of cardboard box that is made up of five layers of material. The term “self” in “self box” suggests that it is a type of box that is able to stand up on its own, without the need for additional support. This could mean that the box has a reinforced bottom or sides to make it sturdier. It could also mean that the box can be folded into a specific shape that allows it to stand up on its own. Without more information, it is hard to provide more accurate details.