I bought the 1-hour timer because it had better reviews. I’m sure the 3 hour works fine, but some folks may not give it a full turn (you need to engage full turn for the switch to work!). I also like the one hour option because it saves me propane. Cutting any high-pressure hose to inline install this timer is not recommended!
https://www.amazon.com/FireMagic-Replacement-Automatic-Timer-Safety/dp/B0062R3XGI

