Imperial 4 In. Metal Worm Gear Clamp

This Imperial 3-in to 4-in Aluminum Increaser allows you to connect pipe of different diameters where air flows from a smaller pipe into a larger pipe.

Crimped on the large end, it increases the diameter of a 3-in round return or exhaust air pipe to 4-in, while maintaining optimal airflow.

The increaser is ideal for general purpose venting applications and is quick and easy to install.