hey everyone

last night while i was looking around my car i found out the passenger side rear mud flap/splash guard was loose then i went down and take a look and found out there were
two screws missing the middle and the one on the outside.i think maybe some shxt hit it while on the freeway but not as i remember.Here the point is the two screws i bought from
dealer does it have a washer or do i just screw it back on and thats it..please advise and
thanks in advance i appreciated