What is Fn + 9 keyboard shortcut for?

Popular programs using this shortcut

What this shortcut does in different programs?

1. Ducky One 2 Mini - F9  
2. RK61 - F9  
3. GMMK (compact) - F9  
4. Corsair K55 RGB - Color pulse, all 3 zones: Red, Green, Blue, Yellow, Cyan, Purple, Orange, White  
5. E-Yooso Z11 - F9  

All programs

All programs using this shortcut, by category.