Warning Labels & Signage GSM Online Label Sales offers a range of Safety Signs and Warning Labels used to highlight hazards and potential dangers around the workplace. More Info Whether you require Prohibition signs (red circle), Warning signs (yellow triangle) or Mandatory signs (blue circle) we offer a selection of artworks for you to choose from. We have available warning labels and safety signs in anodised aluminium, foamex or vinyl to suit the environments and elements that they are subjected to. Supplied as standard sizes and with the option of either adhesive and/or fixing holes to ensure easy and secure application. See below for our full range of Warning Labels and Signage.