Review on Fernco P1056 125 4 Inch Stock Coupling by Jayshawn Cuatlayol

1 1/2 inch ID. I thought it was 1 1/4 inches so it's too big for my needs. I think I should have understood that it is designed for a 1 1/4 inch ID pipe that has a certain thickness that adds up to 1 1/2 inches. You have to know how to measure tubing to get the right fit and I didn't know that. I don't know why they can't just state the inside diameter of this item as 1 1/2 inches. Well, live and learn.