My new favorite tag clip is this "EZ Change ID Clip":
http://www.amazon.com/dp/B00D078UCK/...528360_TE_dp_2

It uses the same secure mechanism as the "Rubit Clip" (my 2nd fav), except the "EZ Change" is smaller because its "C" shape slips directly into a dog tag without needing any extra split-ring. So dog-tags don't hang as far down. Perfect for low wiener dogs! And nobody lost their tags, (yet? <knock-on-wood>).