These are a spring/push-rod appliance placed occasionally while braces are on in order to help with correction of the bite. Initially they may feel a little uncomfortable and rub on the cheeks, but in the same way that you have adjusted to having braces on your teeth, you will also adjust to this appliance. Use wax and warm salt water rinses to assist with the cheeks getting used to the new appliance in place.
If the arms come undone from each other you can usually fix this by opening your mouth quite wide and lining up the two parts of the arms with each other and you should find that they will quite easily slide back into each other. If this doesn't happen fairly easily after a couple of attempts it may mean that one of the arms is bent, which will make it difficult for the two sections to slide into each other. If this happens you can usually make it comfortable by tying each arm to the braces wire or brackets with some floss to keep it out of the way until you can get back to us to fix the problem.