@ Jay...
I thought it helped with getting the lens close to the bottom of the Aixiz housing as well. Hey, I have never actually had an A housing, so really I don't know. It's popular , that's for sure.
@ everyone...
Yes, just the glass here. I do have the 10.5mm houisngs including lens. Not shown as an individual line item or sku, so one would need to say they want a G-1 lens vs. G-2. I will offer it in 12 mm too. FYI my current housings have an odd 8.5mm thread- a bad touch designed into our units about 2 years ago by my Taiwan machining group. We are shifting away from that odd thread. Soon we will be back to our M9 X0.5 like our other lens assemblies. Many do the mods, or custom work on their own, as we sell a lot of lenses. I have some G-1's just sitting around and I know here on LPF it is preferred over the G-2. This is the reason for the thread. It's so the lens alone can be had. For those who don't have the time, skills or machine, Jay's option is a great drop- in, as time has shown.