Question: What's the function of this handle? (Solved)

[St3fan]

EDIT: NVM something was wonky with my driver and now it shows that this thing controls throttle... Just ignore this thread

I just purchased a Logitech joystick to use it as a handbrake. Upon receiving the joystick, I notice there is this handle thing the back of the stick marked "+" and "-". There is a hex screw inside. If I turn the handle, the screw won't move. If I use a 3mm hex wrench to rotate the screw, the handle rotates with it. I'm wondering if this is normal? This this joystick defective? What's the function of this "+""-" handle?

I don't know where I should ask this question so I guess I'll post it here since I think quite a few people are also using this model of joystick as a handbrake.

Thanks in advance. Link to Amazon product page is: https://www.amazon.com/gp/product/B00009OY9U

EDIT: Oops forgot to post pictures: