I'm not sure who the suppliers are in other states, but here in QLD it's A&L Windows, and with them they are called "Boutique Stackers".
Had a quick google search, it does look to be the equivalent of the 300 series with graded handles from Southern Star, I'm assuming that's VIC's Metricon supplier for them.
I love your stacker doors they look amazing and look just like timber! Can I ask did you request to change the handles or was this an option provided to you?
I tried so hard at Studio M to let me change our stacker door handle but they insisted I could only have the D Shape handle
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The handles was $700 upgrade per door (2 handles)