I’m a big fan of pebbled TIR lenses. After buying an S21E I looked around and saw Simon only offers it with TIRs that are smaller and sit underneath the front glass.
After looking around I found 21/23.5 mm diameter and 12.9 mm tall TIRs at Yajiamei that would fit the light perfectly without a front glass: Page Not Found - Aliexpress.com
Only issue, they are only available for 3535 emitters. So I first tried sanding a “slot” into the bottom ring (5mm wide) to fit my XHP50.3 HI. This worked, but while tightening the bezel the very slim remaining plastic parts snapped off, and the lens ripped a part of the silicone off my LED 
So as a second idea I measured how tall the TIR has to be, and sanded the bottom of the TIR off flat so that it could sit on top of the gasket Simon used for the reflector so that the focus distance still matches the LES, then mounted it with a gasket.
OG reflector left, 15° pebbled TIR right:
Picture of the light with TIR, as well as the nice and smooth beam, typical for a pebbled TIR:
