yes seems rockwool greenmix type...
In this moment I am lucky cause I have Orchiata...probably in october also available for sell so I use Orchiata classic + washed river sand + white marble.
But I am trying new technique keeping deflasked seedlings for 3-6 months without media compleately.
I wash away agar,take the flask make holes under and in the cap,put a band of tape in the lower part of the flask to prevent roots take to much light.
Put a small layer of polystirene to prevent water soaking from beneath directly on roots.
Put back the seedlings in the flask(not divideing them,so I compleately not touch roots and so no damages),and close cap.
Every 3 days (or if there is sign of mould forming)a wash roots and spray a mild fertilizer.
At the moment after +1month the seedlings still in very good conditions.
My plan is when the roots start growing back and grow +1-2 cm I will pot them in my media.