Wrister

A Lister (リスター Risut) is a small device shaped like a wristwatch that appears in Digimon Xros Wars which can be used to communicate with one another.

Xros Heart's Listers were originally stored behind Ballistamon's speaker compartment and were later distributed among the group by Shoutmon. It was first put into practical use when Zenjirou was stranded at the top of a bamboo shoot that emerged from under the Village of Smiles. After Digixrossing Starmons into the Star Sword, Taiki uses his Lister to instruct Zenjirou to throw it into the light in order to defeat the Digimon beneath the ground to get rid of the bamboo shoots.