diff --git a/PiSugar-3-Series.md b/PiSugar-3-Series.md
index fbed49e..5410fd9 100644
--- a/PiSugar-3-Series.md
+++ b/PiSugar-3-Series.md
@@ -112,7 +112,7 @@ Click and hold the power button to turn on/off. This feature can be turn off in
 | 4        | Custom function button |                                                                                                                                           |
 | 5        |      Power button      |                                                                                                                                           |
 | 6        |  System reset button   |                                Use when the hardware is in abnormal state, short press will reset PiSugar                                 |
-| 7        |  Extension Interface   | 5V Output, GND, MDAT/MSCL: I2C main interface, no function at this time. SDAT/SSCL: I2C slave interface, connected to Pi's I2C interface. |
+| 7        |  Extension Interface   | 5V Output, GND, MDAT/MSCL: I2C main interface, no function at this time. SDAT/SSCL: I2C slave interface, connected to Pi's I2C interface. PiSugar3 1.27mm Header (use JST 1.25mm connector). PiSugar3 Plus 2.54mm Header  |
 | 8        |      5V Input Pad      |                                                     Connect to USB interface 5V input                                                     |
 | 9        |   Custom Button Pad    |                                        Trigger custom button function when connected to BAT(PAD:2)                                        |
 | 10       |    Power Button Pad    |                                        Trigger power button function when connected to BAT(PAD:2)                                         |