I don't know what type of latch valves the Holman units use as shown below, but we have used 2 of these for over 6 months now with 2 switching periods per 24 hour.
Thought if you could find the type they use maybe be of some help as they have the 216 type 9v alkaline.
https://www.bunnings.com.au/holman-mechanical-misting-tap-timer_p3120836