Made in the UK exclusively by Lambretta upgrades.  Comes in highly polished 304L stainless steel and comes with button allen bolts, flat washers and nyloc nuts.  AF Rayspeed design.
 
This has no mesh, just the grill.
 
Outside diameter is just over 3 1/2inches (90mm).  Requires 2 1/2 inch (63mm) hole cutting out in pane.