Hard Hats Must Be Worn Safety SignConstruction Site Safety Signs Hard Hats Must Be Worn sign is ideal for building sites, informing and instructing the staff and visitors that safety helmets must be worn on site. Conforms to EN ISO 7010 SignageView more of our signage range from Pavement Signs, Flags, Business Signs and Banners. Specifications DimensionsAvailable in sizes A5, A4, A3, A2OrientationPortrait MaterialDetails of each material type can be found on the blue circle tooltip