On Tue, 29 May 2007 10:34:38 +0100, "dennis@home"
wrote:

There is a battery in the unit with the buttons.
They last a couple of years IME.

Yes, I realise in retrospect that one item would need a battery. Not
really a problem, especially if they last a couple of years.

It sounds like you have 1st-hand experience of these devices. Have you
noted any problems?

Thans again,

Mike