Detailed Product Description 1. Can work with all the hosts (HY-2611C, HY-2611E, HY-2611F, HY-2611G)2. When press the buttons on them. The hosts (2611E, 2611F, 2611G) or the pager willdisplay the numbers. 3. There are three kinds of them: One button--2610B1 (service key), two button--2610B2(service and cancel keys, can work with monitor system), three button--2610B3(service, bill and cancel keys, ...