Gemini is a pre-action sprinkler head meaning that it has the benefits of additional protection against accidental water discharge (similar to specialised pre-action sprinkler systems) compacted into a single unit. Gemini features two sprinkler heads, both of these heads must be activated in order for water to be discharged (in a fire situation). Where just of the heads is activated, a fault alarm is generated but no water is discharged prevented accidental water release.