Safety 1st Crystal Clear Monitor Reviews

The Safety 1st Crystal Clear Monitor has worked great for both our boys.  It picks up even their breath and the transmitter is at least five feet away.  I love it that I can take it out to my shop behind the garage and the signal still reaches just fine.  Or there is the option of using the batteries and there is a clip (howbeit not a real well-made one) for my paints so I can work in my landscaping and carry it around with me.  If I get the two units too close together however, the receiver will give off a high pitched squeal.  Also sometimes if I plug the receiver into the same outlet as...