diff --git a/docs/en/product_documents/m5stack-core/m5core_gray.md b/docs/en/product_documents/m5stack-core/m5core_gray.md
index 2119ee71..d1d388e1 100644
--- a/docs/en/product_documents/m5stack-core/m5core_gray.md
+++ b/docs/en/product_documents/m5stack-core/m5core_gray.md
@@ -118,6 +118,8 @@ The a Bottom board on the back of M5Core. It's designed for expanding gpio on M-
   - Arduino - [MacOS](/en/quick_start/m5core/m5stack_core_get_started_Arduino_MacOS) - [Windows_64](/en/quick_start/m5core/m5stack_core_get_started_Arduino_Windows)
   - [MicroPython](/en/quick_start/m5core/m5stack_core_get_started_MicroPython)
 
+- **[The difference between M5Cores](https://github.com/m5stack/M5-Schematic/blob/master/Core/hardware_diff_between_m5cores.md)**
+
 <figure>
   <img src="assets/img/product_pics/core/gray/gray_01.jpg" alt="gray_01" width="500px" height="500px">
 </figure>