The part number for a mounting block to suit duct 900/25/16 is the 900SPMB.
Some of the key features are:
- 84mm mounting centres
- 4 - 25mm X 16mm Entries
- Internal depth of 33mm
- Overall dimensions 116mm (L) X 74mm (W) X 38mm (H)
For further information please visit https://www.clipsal.com/Trade/Products/ProductDetail?catno=900SPMB