*Note: This o-ring is compatible only with PURA systems manufacured in May 2009 or later. The date code is located on the back of the control module. Control modules are replaced every 3 to 5 years, so it is recommended that you consult the owner's manual that was included with your system to ensure you order the correct o-ring. If your system was manufactured before May 2009 you should order part number 151120.