I have used those but I hate timers that have to be reset every time the power goes out so I switched to the intermatic 42 event electronic timers, they have a 5 year battery backup, and also a rechargeable battery in them that charges through the load when the load is off so no ground or neutral, but my all time favorite was the intermatic astro- 42 event, also had the same battery set up as the other, I started using them for about everything from parking lights to automating office lighting, the astro feature will automatically adjust the timer for the change in the sun from summer to winter you have to set the latitude, they never had to be changed, these were the same style as the other one above, and mounted in a outlet opening, depending upon the application if I was controlling a large load I would just add a contactor to them, no more photo cells to fail and no more having to reset the timer when power failed, but I think intermatic caught on and stopped making them, and since we could get them for around $45.00 they were much cheaper then even a T101-104, and way much cheaper then the bigger astro timer that is about the size of a T-101 one of these with a $25.00 clapper relay was still cheaper then any other timer with a photocell.
But like I said they are no longer availble even on ther web site