So far, this seems to be working. I have a cat that loves to sit out on the patio with me, but I needed to tame her killer instinct with birds. It is costly, at $55. Now that I have it, I see that it is simply an ordinary safety collar with a little bell, along with three different brightly colored fabric "tubes," which I think would be very easy to sew at home out of brightly colored fabric. Each one is simply a 12" by 2.5" tube of fabric, open on both ends, that the collar slips into. The collar then fastens at the open ends of the tubes and the bell hangs down at the opening. There may be something about the particular colors and patterns that is effective here. In any event, I notice when I sit out on the patio, I don't hear chirping like I used to, so maybe the birds leave as soon as they see my cat in this. Either that or she's already killed all of them.