In industrial engineering, an MS-CI Pully stands for a Mild Steel Pulley. It is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or to transfer power between the shaft and the belt.

Because they are made from mild steel (low carbon steel), these pulleys are known for being incredibly durable, easy to weld, and cost-effective compared to stainless steel or cast iron alternatives.