RoHS is a European Directive 2002/95/EG about electronic and electrical waste. The corresponding RoHS Directive (Directive on the Restriction of the Use of Certain Hazardous Substances) forbids the use of certain substances in electrical and electronic equipment such as electric motors. The banned substances are lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) or polybrominated biphenyl ethers (PBDEs). The RoHs sticker on the aeration pumps means that they meet this requirement.