A company called Green / Green sells a product called Pet Blinkers: http://www.amazon.com/Pet-Blinker-Dog-Safety-Li… (Patent Pending – Sorry Chris

I don't know how strong these magnets are, but magnets can actually pose a serious health hazard to pets and small children if swallowed, and pets, especially dogs, tend to chew and eat on little things just for the entertainment of it.

Google ” magnet danger ” (no quotes).

http://www.chicagotribune.com/services/newspape…
y/chi-magnetsdec20,0,521277.story

http://durbin.senate.gov/showRelease.cfm?releas…

There are much better alternatives on the market.

Visiglo make good LED dog collars, Miraclebeam make the Cat-Lite Reflective Flashing LED Collar for cats sold by Petsmart (it's breakaway for even more safety) and “Mini Safe-T-Tag” LED I.D. tags are good products for small pets or any pet that wears a collar.

http://visiglo.com/Visiglo-lighted-dog-collar.html

http://www.petsmart.com/product/index.jsp?produ…

http://www.google.com/search?hl=en&rlz=1B3GGGL_…

If you read the reviews on the Pet Blinkers, you'll see that several people complain about the on/off button being too sensitive and shutting off while your pet walks, having shorts and falling apart easily. They're neat looking though.