This is a facesheild bottom based on ArkhamDesigns's Easy FaceShield Frame, which was itself a remix of the common facesheild design. This is designed to slide on, negating the need for any hole punching.

It grips pretty well. Useful for helping the shield hold its shape.

No need to line up any holes. Once attached to the top part, carefully place the shield's sheet in the grove, wiggle the two parts of the bottom piece to slide it on.