Sodastream tanks have a propietary thread pattern and can only be filled by Sodastream. I also called Windsor and they said that a 2lb. CO2 tank is the minimum size they will refill. So they will not refill Sodamod paintball tanks, if you're thinking of going that way.
They refill co2 tanks. If a soda stream is co2 and has similar fittings you should be good.
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