Help identify a MARES model and shaft size

I have an old working MARES speargun that I’m pretty sure it’s a Frontiersman / Sten. I need a spare shaft, but the problem is that I have some confusion about the exact Stean model. Actually Mares website has two types of Stean: STEN and STEN 11. The Sten have a 8mm shaft and the Sten 11, have

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Is this a good starter speargun? : r/Spearfishing

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Ø 7 mm shaft

Help identify a MARES model and shaft size

Mares Cyrano HFT Speargun Pneumatic, 42% OFF