Thumb glove for bassists?

[Hamrhed]

I have seen Mark King from Level 42 use a sleeve on his thumb for slapping, but recently I noticed Geezer Butler (Heaven & Hell at RCMH dvd) used something similar on his right hand thumb... anyone know specifically what this is or where they can be found?

[superbassman2000]

off the top of my head it sounds like you are talking about a slap ring

http://www.slapring.com/en/home/index.php