This tube is the outer part of a 1 inch (25.4mm) to 7/8 inch (22.2mm) telescoping tube system. This tube is designed to clamp a painted 7/8 inch tube. It has two clamping slots, one on each end. You can use this to clamp two 7/8 inch tubes by adding a second collar clamp. This tube is powder coated aluminum, 6 inches (150mm) long, 1 inch (25.4mm) OD, and 0.902 (22.9mm) ID.
Used it to add some length to the steering mast of my Bike Friday Sat-R-Day. 4 stars because shipping to Canada was very expensive.