The new SMART 503, a drop-in upgrade for your CPN Hydroprobe, dramatically enhances the functionality and performance of your existing gauge. The upgrade is specifically designed to provide a variety of new, operator friendly features that bring today’s technology to the Hydroprobe . CPN’s SMART 503 offers a new 4 x 20 character backlit LCD, longer lasting lithium-ion batteries and the ability to store and download test data via a built-in USB port.