Here's what other sites are saying:
The G3 Onyx Bellowed Boot Shim is a required accessory when using the Onyx with Scarpa's F-series AT boots or other bellowed boots. Does not hinder ski flex and works with G3 Onyx crampons.
Required when using the ONYX or RUBY binding with Scarpa's F-series AT boots or other bellowed boots, G3's ONYX / RUBY Bellowed Boot Shim is easy to install and remove. They do not hinder ski flex and they work well with ONYX crampons as well.
- Mountain Gear
G3 Onyx Brake
G3 Onyx Crampon
G3 Onyx Mounting Plate Kit
Black Diamond STS Kit
Black Diamond STS Tailhook
Black Diamond Glop Stopper Wax
Marker Tour Crampon
Black Diamond Fritschi Diamir Vipec 12 Safety Tech Color Clip Set