ASI has a minimum order requirement. Orders smaller than the required minimum have a longer lead time as we need to consolidate onto a "stock" order. If you need a faster lead time, simply exceed the minimum order amount.
Click Here
Take particular note of the reference to the Drywall Clamp no. 39 as seen here:
This might be easier.
To summarize:
Wet wall installation: Apply grout to back of unit and on perforated lugs and then push unit into RWO. Set flanges flush with face of finished wall.
Dry wall installation: Fasten unit to wall opening with No10 screws (supplied) through dimpled holes at back of shell, or use dry wall clamp model No39.