VKB-SIM

Hi everyone, I recently bought the STECS Space Throttle System – Standard Left-Hand (SKU: VKBSIM-T-STECS-STG-STD-L) and am very happy with it! However, I haven't been able to locate "Slider 1" yet; it shows up in the VKB Device Config and even outputs a mid-range value. Can anyone explain where this axis is or what it's for?

By default it should be one of the axes used for MB1 ministick. If the ministick is not present the axes are just there.