The Speed Chuck is a great add-on to Lezyne floor pumps. It screws onto the Flip-Chuck head at a right angle to make it easy to fit in a disc wheel's valve cavity. It uses washers so you can just press on the chuck without fiddling with screwing on threads. And because it's added beyond the Flip-Chuck, you still have use of the bleeder valve. While the Speed Chuck comes standard with all current Lezyne floor pumps, it can be lost. And older pumps didn't come with it, so it's a nice upgrade if you've had your Lezyne for a while. The Lezyne Speed Chuck is a Presta-only Slip-Fit System adapter designed for fast valve engagement. The 90-degree bend is compatible with disc wheels. The 2-piece Composite Matrix design makes replacing O-ring seals quick and easy. It is compatible with all ABS Flip-Thread Chucks and available on all Flip-Thread Chuck equipped pumps, and the color is Black.