I didn't find anything regarding M840, but it looks like your 2020 Kia Stinger most likely has Rhino-Rack Vortex Aero Crossbars # RRVA126B-2. For those crossbars, use Rhino-Rack Locking End Caps for Vortex Aero Crossbars # RRVA-LEC4 for 4 locking end caps. view full answer...