This adapter is suitable for the Mini duotight Regulator to fit a threaded AU Sodastream cylinder.
It will also fit the KL08631 Kegland Branded 450gm Sodastream cylinder.  

PLEASE NOTE: The adaptor can only engage the cylinder via the round knob. It cannot retract / dissengage.
Always use two spanners / adjustable wrenches when attaching this to your sodastream.

Specifications: 
5/8' 18TPI 18UNF male to G1/2 female