That device type is likely part of an update device pack (not part of the original set of definitions shipped with 11.5).
We'll look into getting this device pack installed in the various collab labs.
If you are using a reserved Sandbox (which gives you full CUCM admin rights), and have access to download the device pack from Cisco.com (https://software.cisco.com/download/home/286306100/type/282074299/release/11.5%25281.14064%2529), you could install it yourself. (Would not persist across reservations, unfortunately...)