Heavy-duty cords will have a marking on the insulation such as letters which indicates its properties.
<h3>What are Heavy duty cords?</h3>
Heavy duty cords comprises of insulators which helps prevent cases of electric shock. There are usually letters written on them which indicates the nature of insulation and other properties.
For example, the "S" in "SO" stands for "Extra Hard Service and the "O" stands for oil resistant.
