Anet A8 Cooler 40mm Fan Duct upper

NVBigBlue created and published a design for an Anet A8 Dual Extrusion upgrade (http://www.thingiverse.com/thing:1733096).
I am converting my Sintron Prusa I3 using this upgrade, and it works very well, but I managed to get 40mm radial fans from Amazon - https://www.amazon.co.uk/gp/product/B01EZQL652/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1. These use a different upper duct to the 50mm fan that NVBigBlue used for his part cooling setup, so I made this adaptor. It's screwed to the side of the