This Caution Cows With Calves Can Be Aggressive Sign is perfect for use as a warning sign where cows and calves are present. Designed to be used outside in a wide range of situations on farms, estates, fields and roadsides where there may be cows and calves, it is fully waterproof and is used to inform and warn people of a potential hazard that may be present and care should be exercised. The Health and Safety (Safety Signs and Signals) Regulations 1996, recommend that where a risk cannot be completely removed a suitable warning sign should be displayed to warn people of a possible danger.