The RISE Armament RA-140 Super Sporting Trigger uses set screws that must be accessed from inside the trigger for installation. The RISE Armament Rave 140 AR Drop-In Trigger uses springs at the bottom of the housing for easier installation instead of set screws. Both can be used in a 9mm AR but I recommend using the RISE Armament Rave 9mm PCC Trigger at the link below for a 9mm AR.
https://www.opticsplanet.com/rise-armament-rave-pcc-trigger-with-anti-walk-pins.html