4000H2 is the part number of the mounting frame supplied with Z4025H2.

Please go to the following links below and check under the Documentation Tab for more information.
Australia - https://www.clipsal.com/products/detail?CatNo=4000H2&itemno=4000H2-WE&backto=/search?q=4000H2&tab-document-1=0
New Zealand - https://www.pdl.co.nz/products/detail?CatNo=4000H2&itemno=4000H2-WE&backto=/search?q=4000H2&tab-document-1=0