Let me get in contact with steve@mace and see what's going on. I thought they was already selling the 25mm, 6mm, and 12mm's last time I talk to them. Maybe they are in the process of still updating everything.
EDIT: Just talk to steve and they are still updating the site but here are the part numbers for anyone that need them to order,
MI621(6mm), MI622(12mm) and MI623(25mm)
http://maceengineering.com.au/