It helps to change direction at 90 degree, and is commonly used to connect hoses to pumps, deck drains and valve.SR 90 degree elbow is the same as the pipe elbow mentioned above, but the diameter is shorter. Therefore, this kind of steel elbow is often used when space is not enough.A 90 degree elbow attaches readily to plastic, copper, cast iron, steel and lead. It can also attach to rubber with stainless steel clamps. Available in many materials like silicon, rubber compounds, galvanized steel etc.