The 3/4" Black 90° elbow has a variety of uses but its primary use is to Change the direction of two pipes to a 90° angle. Each end of the fitting allows for a pipe end to be inserted to meet the opposite pipe end. Elbows are commonly used at the end of railing sections, or to change the direction of a project with a right angle. Two set screws are included with the fitting to tighten for security.