I have an installed COGuardian.  First unit went defective, second seems to
be working fine (new and improved version with a fan).  Never have to think
about it anymore.  Great if you have space to put it.  I mounted mine on the
rear baggage bulkhead.

Matt
>
> As far as a reliable and reasonably priced electronic CO detectors
> go...which one is the best bang for the buck.  I'm going to pick one
> up...tired of that little tab always flying around the cockpit.
>
>