Unexpected fitment - Vortex Diamondback Tactical Rifle Scope Sunshade

I purchased this shade for a Vortex Diamondback scope but it ended up not fitting the particular model. But as I was boxing it up to send back I thought, to heck with it and tried it on my 40mm objective Nikon scope(s) and to my surprise it fit well. The is a minor difference in the outside diameter(s) of the shade and the scope but otherwise its perfect. To anyone in the know about Nikon rifle optics, Nikon no longer makes rifle optics, nor associated accessories so this is a good substitute for a Nikon sunshade.