Circuit Board V3818TC ( V3818-01,-02,-03,-04 )with 3 button controller used for Clack WS1 / W1.25 timer clock Valves and other "brands" that use the Clack type of valve under their private label.3 button boards all come with Battery Back up now. Older versions did not ( cross reference with old PN V3108TC )
Photos reference the older and newer ( direct replacement ) design.
New design comes with new front "decal" to match the new slightly larger Screen lay out.
If LABEL on the board that says = V3818TB --- TB just means that it was originally programed for a backwash only valve, they are interchangeable.
The boards can be programmed for water conditioning or filter backwash.