They look like rope, but they're made of plastic, in the team colors. Also important: they look stupid.
Look, lads, everyone knows to which team you belong. Because, in case you didn't notice when getting dressed for this game, you are wearing exactly the same thing as everyone else in the dugout. It is called a uniform, and it is designed for the express purpose of making you recognizable as part of a group. Were you really so confused that you needed the extra hint of a plastic piece of junk?
This goes for you too, England cricket. Those little England bracelets are dumb.
Update: It has been brought to my attention that these excrescences are probably of the type that is made of magnets and has approximately the same effect on your baseball prowess as being bitten by a radioactive spider, or something. Fair enough. They're still heinous.