These openers use rare earth magnets which are recessed in the back. They attach to any metal surface and when you open a bottle they catch and hold the tops. ( neat idea some other LBJ member shared a while ago)
Jim-I've only bought new ones - mostly thru Amazon.com. These companies sell them:
Bottle Opener Dude
Wine Reserve Inc
Kegconnection
Tags America
Starr
Get Schnockered
Innovative Outdoor Network
Rliaqble Sales
They are pricey though- aqvg $8.00 and up