I.D. Your Valve
Some water treatments units have a name to identify the manufacturer and some do not. Below is pictures of the most common valve used with no identifying name.
Autotrol Timer 155
Autotrol Timer 255
Fleck 5600 Timer Valve
The 5600 timer has pins that can be set for 1,2,3,4,6 & 12 days between regenerations.
Fleck 5600 Meter
The 5600 meter has a cable coming from the back that attaches to the dome in the rear of the valve.