Vorsk produces gas magazines for the VM9 series in both standard (around 24-25 rounds) and extended (around 48-50 rounds) capacities
 
VORSK VM9 Series 24R STD Gas Magazine (VGM-05-01)
Capacity: This is the standard capacity gas magazine, holding approximately 24 rounds.
Construction: It features a metal body with polymer feed lips, a follower, and a protective base plate.
Compatibility: It is compatible with all Vorsk VM9 series and VM9 OSIRIS GBB pistols.