The Pulley Triple in Line (Brass) is a physics laboratory apparatus designed to demonstrate compound pulley systems. It consists of three brass pulleys mounted in a straight line on a rigid frame.Below is a concise description for content purposes.triple in-line brass pulley is a high-performance, durable tool designed for a variety of mechanical and lifting applications. Featuring three aligned pulleys made from premium-grade brass, this device ensures smooth operation, exceptional load-bearing capacity, and resistance to wear and rust.