diff --git a/data.cpp b/data.cpp
index 71f9035..b05bc04 100755
--- a/data.cpp
+++ b/data.cpp
@@ -918,6 +918,9 @@
 	mConst.SetValue("tw_include_nano", "0");
 #endif
 
+	mData.SetValue("tw_flash_both_slots", "0");
+	mData.SetValue("tw_is_slot_part", "0");
+
 	mData.SetValue("tw_enable_adb_backup", "0");
 
 	if (TWFunc::Path_Exists("/sbin/magiskboot"))
diff --git a/gui/Android.mk b/gui/Android.mk
index c4d938a..32c0d5b 100755
--- a/gui/Android.mk
+++ b/gui/Android.mk
@@ -103,6 +103,9 @@
 ifeq ($(TW_EXCLUDE_NANO), true)
     LOCAL_CFLAGS += -DTW_EXCLUDE_NANO
 endif
+ifeq ($(AB_OTA_UPDATER),true)
+    LOCAL_CFLAGS += -DAB_OTA_UPDATER=1
+endif
 
 LOCAL_C_INCLUDES += \
     bionic \
diff --git a/gui/action.cpp b/gui/action.cpp
index 29fa945..2ca2161 100755
--- a/gui/action.cpp
+++ b/gui/action.cpp
@@ -1817,16 +1817,41 @@
 int GUIAction::flashimage(std::string arg __unused)
 {
 	int op_status = 0;
+	bool flag = true;
 
 	operation_start("Flash Image");
 	string path, filename;
 	DataManager::GetValue("tw_zip_location", path);
 	DataManager::GetValue("tw_file", filename);
-	if (PartitionManager.Flash_Image(path, filename))
-		op_status = 0; // success
-	else
-		op_status = 1; // fail
 
+#ifdef AB_OTA_UPDATER
+	string target = DataManager::GetStrValue("tw_flash_partition");
+	unsigned int pos = target.find_last_of(';');
+	string mount_point = pos != string::npos ? target.substr(0, pos) : "";
+	TWPartition* t_part = PartitionManager.Find_Partition_By_Path(mount_point);
+	bool flash_in_both_slots = DataManager::GetIntValue("tw_flash_both_slots") ? true : false;
+
+	if (t_part != NULL && (flash_in_both_slots && t_part->SlotSelect)) 
+	{
+		string current_slot = PartitionManager.Get_Active_Slot_Display();
+		bool pre_op_status = PartitionManager.Flash_Image(path, filename);
+
+		PartitionManager.Set_Active_Slot(current_slot == "A" ? "B" : "A");
+		op_status = (int) !(pre_op_status && PartitionManager.Flash_Image(path, filename));
+		PartitionManager.Set_Active_Slot(current_slot);
+
+		DataManager::SetValue("tw_flash_both_slots", 0);
+		flag = false;
+	}
+#endif
+	if (flag)
+	{
+		if (PartitionManager.Flash_Image(path, filename))
+			op_status = 0; // success
+		else
+			op_status = 1; // fail
+	}
+	
 	operation_end(op_status);
 	return 0;
 }
diff --git a/gui/partitionlist.cpp b/gui/partitionlist.cpp
index 16e0997..9c5b58e 100644
--- a/gui/partitionlist.cpp
+++ b/gui/partitionlist.cpp
@@ -179,6 +179,8 @@
 		pos = variablelist.find(searchvalue);
 		if (pos != string::npos) {
 			mList.at(i).selected = 1;
+			TWPartition* t_part = PartitionManager.Find_Partition_By_Path(mList.at(i).Mount_Point);
+			DataManager::SetValue("tw_is_slot_part", t_part != NULL ? (int) t_part->SlotSelect : 0);
 		} else {
 			mList.at(i).selected = 0;
 		}
@@ -272,6 +274,8 @@
 					mList.at(item_selected).selected = 0;
 				else
 					mList.at(item_selected).selected = 1;
+					TWPartition* t_part = PartitionManager.Find_Partition_By_Path(mList.at(item_selected).Mount_Point);
+					DataManager::SetValue("tw_is_slot_part", t_part != NULL ? (int) t_part->SlotSelect : 0);
 
 				int i;
 				string variablelist;
diff --git a/gui/theme/common/landscape.xml b/gui/theme/common/landscape.xml
index 5d3f5ea..4be49ea 100755
--- a/gui/theme/common/landscape.xml
+++ b/gui/theme/common/landscape.xml
@@ -372,7 +372,10 @@
 					<condition var1="tw_selectimage" var2="1"/>
 					<condition var1="tw_filename" op="modified"/>
 				</conditions>
-				<action function="page">flashimage_confirm</action>
+				<actions>
+					<action function="set">tw_is_slot_part=0</action>
+					<action function="page">flashimage_confirm</action>
+				</actions>
 			</action>
 
 			<action>
@@ -711,6 +714,30 @@
 				<listtype name="flashimg"/>
 			</partitionlist>
 
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="0"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%col1_x_left%" y="%row14a_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_false"/>
+				<action function="set">tw_flash_both_slots=1</action>
+			</button>
+
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="1"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%col1_x_left%" y="%row14a_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_true"/>
+				<action function="set">tw_flash_both_slots=0</action>
+			</button>
+
 			<slider>
 				<text>{@swipe_flash=Swipe to confirm Flash}</text>
 				<actions>
diff --git a/gui/theme/common/languages/en.xml b/gui/theme/common/languages/en.xml
index 868dbea..a6074fd 100755
--- a/gui/theme/common/languages/en.xml
+++ b/gui/theme/common/languages/en.xml
@@ -740,6 +740,7 @@
 		<string name="unmount_system_err">Failed unmounting System</string>
 		<string name="flash_ab_inactive">Flashing A/B zip to inactive slot: {1}</string>
 		<string name="flash_ab_reboot">To flash additional zips, please reboot recovery to switch to the updated slot.</string>
+		<string name="flash_ab_both_slots">Flash to both slots</string>
 		<string name="ozip_decrypt_decryption">Starting Ozip Decryption...</string>
 		<string name="ozip_decrypt_finish">Ozip Decryption Finished!</string>
 		<string name="restore_system_context">Unable to get default context for {1} -- Android may not boot.</string>
diff --git a/gui/theme/common/portrait.xml b/gui/theme/common/portrait.xml
index 4bcaf57..80ee07d 100755
--- a/gui/theme/common/portrait.xml
+++ b/gui/theme/common/portrait.xml
@@ -329,7 +329,10 @@
 					<condition var1="tw_selectimage" var2="1"/>
 					<condition var1="tw_filename" op="modified"/>
 				</conditions>
-				<action function="page">flashimage_confirm</action>
+				<actions>
+					<action function="set">tw_is_slot_part=0</action>
+					<action function="page">flashimage_confirm</action>
+				</actions>
 			</action>
 
 			<action>
@@ -662,6 +665,30 @@
 				<listtype name="flashimg"/>
 			</partitionlist>
 
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="0"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%indent%" y="%row19a_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_false"/>
+				<action function="set">tw_flash_both_slots=1</action>
+			</button>
+
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="1"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%indent%" y="%row19a_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_true"/>
+				<action function="set">tw_flash_both_slots=0</action>
+			</button>
+
 			<slider>
 				<text>{@swipe_flash=Swipe to confirm Flash}</text>
 				<actions>
diff --git a/gui/theme/common/watch.xml b/gui/theme/common/watch.xml
index 4ff783a..8b8fdd7 100755
--- a/gui/theme/common/watch.xml
+++ b/gui/theme/common/watch.xml
@@ -442,7 +442,10 @@
 					<condition var1="tw_selectimage" var2="1"/>
 					<condition var1="tw_filename" op="modified"/>
 				</conditions>
-				<action function="page">flashimage_type</action>
+				<actions>
+					<action function="set">tw_is_slot_part=0</action>
+					<action function="page">flashimage_type</action>
+				</actions>
 			</action>
 
 			<action>
@@ -860,6 +863,30 @@
 				<listtype name="flashimg"/>
 			</partitionlist>
 
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="0"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%col2_x_left%" y="%row11_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_false"/>
+				<action function="set">tw_flash_both_slots=1</action>
+			</button>
+
+			<button style="checkbox">
+				<conditions>
+					<condition var1="tw_is_slot_part" op="=" var2="1"/>
+					<condition var1="tw_flash_both_slots" op="=" var2="1"/>
+					<condition var1="tw_has_boot_slots" var2="1"/>
+				</conditions>
+				<placement x="%col2_x_left%" y="%row11_y%" textplacement="6"/>
+				<text>{@flash_ab_both_slots=Flash to both slots}</text>
+				<image resource="checkbox_true"/>
+				<action function="set">tw_flash_both_slots=0</action>
+			</button>
+
 			<button>
 				<placement x="%col1_x_left%" y="%row11_y%"/>
 				<highlight color="%highlight_color%"/>