We've seen a few vertical grips out there with the ability to hold a flashlight, but CAA Airsoft Division have released their own polymer version which comes with an addition 1 inch rail so you can add something else to it if you want!
You can loosen the thumb screws so you can fit on the rails of your AEG. Insert the flashlight into the FGA then tighten with the hex key, that it comes with, to keep it safety tucked inside.
Disclaimer: All aftermarket upgrade parts require necessary skill or modification to install and assemble, please consult with your airsoft technician if needed.