... Safely up to 20 times a day for each day - what do you normally ... more

You just got us right. To a regular ventilation / venting our cellar by a [[ASIN: B002MPK84E tube insertion fan]] to ensure we use this, for over a year incredibly reliable and inexpensive timer that enables us in the warmer months, the fan in the first place to let time and again run over night or in the cold during the day for an hour.

The clock is no radio clock - Because it's not about exact to the second control in our application, the accuracy is sufficient) - very well. Using the description of the adjustment is to be made quickly and easily, for us, of course, super easy because the switching cycle for each day is the same.
Also switching from winter to summer time and again goes back with one keystroke.

Important to me was a reliable and solid clock and was delivered exactly one that will inspire you in terms of their settings probably many. Moreover, the brand has "revolt" quite a name.

A truly optimal price / performance ratio and a "highly recommended!"

Note 1:
That the battery is not to change * is, I feel is not necessarily a disadvantage, especially when the clock permanently hangs like in our case the mains. When I think of our audio / TV systems also have this built-in batteries that with us for years doing their duty without having been substituted.

* Surely I'm not there, because back a bolt, elongated lid is available in size of a AAA battery. However, I'll (incidentally 5 years) not open it during the warranty period), there is in the description: "A battery change is not provided".

NB:
To have the user manual (A5 / 1 page) in an emergency at hand, I have this enlarged to A4 and laminated. Now depends on hand and easy to read next to the clock in the basement.

Note 2 / Jan 2015:
Since already more than 4 years, the clock works without any problem in daily switching cycle.