same as the other two on that side...
hex flange head M8 x 1.25 x 16 use 10mm wrench or socket i think the one on the driver's side is 20mm long to account for the thicker surface of the bracket.
that round nut in the cage on the bottom of the intercooler has a knurled finish so it is just press fit...many times that nut will break free attempting disassembly and just spin. you might have to add a flange nut for reassembly. if the original nut is still in that cage on the intercooler, just don't torque the snot out of it upon reassembly.