The media trays that are installed on the chassis. The media trays are listed as a bitmap. The bitmap is a string containing a list of 1's and 0's that is as long as the number of media trays supported. If a media tray is installed in a bay, a 1 is present in the string in the position representing the bay ID as read from left to right. For example, if media trays are installed in bays 1, and 2 media trays are, the string would look like '10'.