VEVOR Workbench Corner Brackets, 5mm Thick Steel Shop Table Bracket Kit, 8 PCs Workbench Bracket Kit, Right Angle Shop Table Corner Brackets with Hardware Kit, Joint Fastener for Desk Edge, Family DIY

Hi - What is the thickness of the material these brackets are made from? I have read where they are 5mm thick and then another place it says they are 4mm thick. Thanks.