The ASO activates when back pressure builds in the product line (due to a float being activated or a bladder tank be full). The activated ASO stops the drain from continuing to run by stopping water from entering the RO membrane housing. Once the back pressure is released, water production will resume. Hydraulic Automatic Shut-Off Kit Includes: - Quick Connect Automatic Shutoff Valve - Quick Connect Check Valve - Approximately 24 inches of tubing included