Rack ears are NOT supplied with the Xone:92 (MK2), see the User Guide for details.

Part code > Description
X:922-RK19/X > XONE:922 19" RACK MOUNT KIT

Rack ears were supplied with the Xone:92 (MK1), see the User Guide for details.

Part code > Description
X:92-RK19SG > RACK EAR ASSY XONE:92 19"     (STORM GREY)  

Should you need more, please order through your dealer or local Allen & Heath distributor.