Sennheiser IE 900 In-Ear Headphones - Manual (Page 4)

6.
R–
R+
L+
L–
L+
R+
L–/R–
L+
L–
R+
R–
GND nc
L–/R–
L+/R+
MMCX
2.5 mm
3.5 mm
4.4 mm