Universal Bath, Jetted Tub and Spa Air Button for controlling pumps, blowers and lights on air control systems. Fits various air systems like Tecmark, Brett, Len Gordon and more. Air Button measures 1-3/4"" across the flange, 1.25"" OD across the bottom, and fits hole sizes from 1.25"" to 1.6 inches wide. Waterway air button operates with 1/8"" air hose, sold separately. Air buttons are used for controlling bath and jetted tub pumps and blowers, or spa equipment using air activated spa and bath controls, not digital systems. Includes Lock Nut or Lock Ring to secure to underside of spa.