wrote in message
oups.com...
They have a convenient spray that allows you to test the sensor
elements of a smoke detector

I have been a proponent for years of NEVER EVER buying CO detectors that are
not the digital variety. Those who give you the current or past levels of
CO in a digital format. If it's a beep/no beep type and the danger zone is
400 (pick a number), and you only get to 399, it doesn't go off. I like to
know if there's CO present at all, and if it is just a little, or
approaching the beep level.

Just MHO, YMMV.

Steve