Warning of Biological Hazard (ZW11) safety sign is a yellow and black triangle with a biohazard symbol in the middle of the triangle. 
 It is used in the labeling of biological materials that carry a significant health risk, including viral samples and used hypodermic needles. In unicode the symbol is as per the Sign we sell online
The correct biological hazard warning signs allow for the material to be handled correctly, which drastically reduces the risk of an accident. 
Biohazard signs and labels are used to alert staff, visitors, freight and emergency services to take precautions on potential exposure, and on handling procedures. 
SABS standard safety sign