User blog comment:Tekkphreke/Gotei 13 VS Vandenreich Round 2 Line up/@comment-8438917-20130703063303

Like various others within the Vandenreich, all members of the Stern Ritter carry on their person a round, unnamed device that is roughly the size of a person's palm and has the Vandenreich insignia etched into its surface. When activated, this device is capable of stealing a single currently released Bankai in the immediate vicinity.[9] The medallion's owner can then proceed to use the stolen Bankai's power at will,[10] even after the original owner of the Bankai has died.[11] However, they are unable to exploit this power fully, as noted by Yamamoto.[12]

heres link 2 the thing, something happened with replies, they got messed up

http://bleach.wikia.com/wiki/Stern_Ritter