The devices you are talking about are called PinSavers. They are a pin back that attaches with a set screw and an allen wrench. These will secure a pin to a lanyard, book, jacket and give you a little peace of mind. JoJo_CT introduced me to these during the August Pin Event and they are awesome! They sell for $5.95 for a package of 10 (with the wrench). I sell a lot of these with our lanyards and so far I have gotten a lot of complements on how well they work. If you need more information, please let me know.
Jeff