Seems convoluted that you would need a "another 4 hole base" to use a different coil, if I am reading that right.
It is cheap though at $10.50:
Eleaf iJust 2 Pyrex Glass BDC(Bottom Dual Coil) Atomizer - 5.5ml
Would rather just see an "upgraded" GS Air M made out of stainless steel - keeping the price the same. The "new" Subtank Mini seems to cover a lot of bases, just the price is high... if a new GS Air functioned closer to a ST mini at the "value" price point that would be nice. My impression (which is worth nothing) is Eleaf needs a real plan... not more products.