diff --git a/Firmware/Marlin_main.cpp b/Firmware/Marlin_main.cpp
index f3528ca9..2a261db2 100755
--- a/Firmware/Marlin_main.cpp
+++ b/Firmware/Marlin_main.cpp
@@ -8569,14 +8569,6 @@ Sigma_Exit:
 	}
 	break;
 
-    /*!
-    ### M666 - Enter experimental menu
-    Only used by Prusa
-    */
-    case 666:
-        menu_submenu(lcd_experimental_menu);
-    break;
-
     /*!
     ### M999 - Restart after being stopped <a href="https://reprap.org/wiki/G-code#M999:_Restart_after_being_stopped_by_error">M999: Restart after being stopped by error</a>
     @todo Usually doesn't work. Should be fixed or removed. Most of the time, if `Stopped` it set, the print fails and is unrecoverable.
diff --git a/Firmware/eeprom.h b/Firmware/eeprom.h
index bfc81d82..ee7fa39e 100644
--- a/Firmware/eeprom.h
+++ b/Firmware/eeprom.h
@@ -359,6 +359,8 @@ static_assert(sizeof(Sheets) == EEPROM_SHEETS_SIZEOF, "Sizeof(Sheets) is not EEP
 | ^					| ^			| ^										| 00h 0			| ^						| LCD backlight mode: __Dim__						| ^				| ^
 | 0x0D30 3376		| uint16	| EEPROM_BACKLIGHT_TIMEOUT				| 01 00 - ff ff | 0a 00h 65535			| LCD backlight timeout: __10__ seconds				| LCD menu		| D3 Ax0d30 C2
 | 0x0D2C 3372		| float		| EEPROM_UVLO_LA_K						| ???			| ff ff ff ffh			| Power panic saved Linear Advanced K value			| ???			| D3 Ax0d2c C4
+| 0x0D2B 3371		| uint8		| EEPROM_ALTFAN_OVERRIDE				| 0-1			| 00h					| ALTFAN override									| LCD menu		| D3 Ax0d2b C1
+| 0x0D2A 3370		| uint8		| EEPROM_EXPERIMENTAL_VISIBILITY		| 0-1			| 00h					| Experimental menu visibility						| LCD menu		| D3 Ax0d2a C1
 
   
 | Address begin		| Bit/Type 	| Name 									| Valid values	| Default/FactoryReset	| Description 										| Gcode/Function| Debug code
@@ -562,9 +564,10 @@ static Sheets * const EEPROM_Sheets_base = (Sheets*)(EEPROM_SHEETS_BASE);
 #define EEPROM_UVLO_LA_K (EEPROM_BACKLIGHT_TIMEOUT-4) // float
 
 #define EEPROM_ALTFAN_OVERRIDE (EEPROM_UVLO_LA_K-1) //uint8
+#define EEPROM_EXPERIMENTAL_VISIBILITY (EEPROM_ALTFAN_OVERRIDE-1) //uint8
 
 //This is supposed to point to last item to allow EEPROM overrun check. Please update when adding new items.
-#define EEPROM_LAST_ITEM EEPROM_ALTFAN_OVERRIDE
+#define EEPROM_LAST_ITEM EEPROM_EXPERIMENTAL_VISIBILITY
 // !!!!!
 // !!!!! this is end of EEPROM section ... all updates MUST BE inserted before this mark !!!!!
 // !!!!!
diff --git a/Firmware/ultralcd.cpp b/Firmware/ultralcd.cpp
index bb1d2c71..24e33168 100755
--- a/Firmware/ultralcd.cpp
+++ b/Firmware/ultralcd.cpp
@@ -2113,6 +2113,7 @@ static void lcd_support_menu()
 		bool is_flash_air;             // 1byte
 		uint8_t ip[4];                 // 4bytes
 		char ip_str[3*4+3+1];          // 16bytes
+        uint8_t experimental_menu_visibility;
 	} _menu_data_t;
     static_assert(sizeof(menu_data)>= sizeof(_menu_data_t),"_menu_data_t doesn't fit into menu_data");
 	_menu_data_t* _md = (_menu_data_t*)&(menu_data[0]);
@@ -2126,6 +2127,14 @@ static void lcd_support_menu()
             sprintf_P(_md->ip_str, PSTR("%d.%d.%d.%d"), 
                 _md->ip[0], _md->ip[1], 
                 _md->ip[2], _md->ip[3]);
+        
+        _md->experimental_menu_visibility = eeprom_read_byte((uint8_t *)EEPROM_EXPERIMENTAL_VISIBILITY);
+        if (_md->experimental_menu_visibility == EEPROM_EMPTY_VALUE)
+        {
+            _md->experimental_menu_visibility = 0;
+            eeprom_update_byte((uint8_t *)EEPROM_EXPERIMENTAL_VISIBILITY, _md->experimental_menu_visibility);
+        }
+        
     } else if (_md->is_flash_air && 
         _md->ip[0] == 0 && _md->ip[1] == 0 && 
         _md->ip[2] == 0 && _md->ip[3] == 0 &&
@@ -2210,6 +2219,12 @@ static void lcd_support_menu()
   MENU_ITEM_SUBMENU_P(_i("Voltages"), lcd_menu_voltages);////MSG_MENU_VOLTAGES c=18 r=1
 #endif //defined VOLT_BED_PIN || defined VOLT_PWR_PIN
 
+  if (_md->experimental_menu_visibility)
+  {
+    MENU_ITEM_SUBMENU_P(PSTR("Experimental"), lcd_experimental_menu);
+  }
+
+
 #ifdef DEBUG_BUILD
   MENU_ITEM_SUBMENU_P(PSTR("Debug"), lcd_menu_debug);////c=18 r=1
 #endif /* DEBUG_BUILD */
@@ -8997,6 +9012,13 @@ void menu_lcd_longpress_func(void)
         lcd_quick_feedback();
         return;
     }
+    if (menu_menu == lcd_hw_setup_menu)
+    {
+        // only toggle the experimental menu visibility flag
+        lcd_quick_feedback();
+        lcd_experimental_toggle();
+        return;
+    }
 
     // explicitely listed menus which are allowed to rise the move-z or live-adj-z functions
     // The lists are not the same for both functions, so first decide which function is to be performed
@@ -9161,6 +9183,16 @@ void lcd_crash_detect_disable()
 }
 #endif
 
+void lcd_experimental_toggle()
+{
+    uint8_t oldVal = eeprom_read_byte((uint8_t *)EEPROM_EXPERIMENTAL_VISIBILITY);
+    if (oldVal == EEPROM_EMPTY_VALUE)
+        oldVal = 0;
+    else
+        oldVal = !oldVal;
+    eeprom_update_byte((uint8_t *)EEPROM_EXPERIMENTAL_VISIBILITY, oldVal);
+}
+
 void lcd_experimental_menu()
 {
     MENU_BEGIN();
diff --git a/Firmware/ultralcd.h b/Firmware/ultralcd.h
index 971c07b6..95a3cec1 100755
--- a/Firmware/ultralcd.h
+++ b/Firmware/ultralcd.h
@@ -257,6 +257,7 @@ enum class WizState : uint8_t
 
 void lcd_wizard(WizState state);
 
+extern void lcd_experimental_toggle();
 extern void lcd_experimental_menu();
 
 #endif //ULTRALCD_H