diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/operations/FetchActivityOperation.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/operations/FetchActivityOperation.java
index 21bc3928..9019013b 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/operations/FetchActivityOperation.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/operations/FetchActivityOperation.java
@@ -27,7 +27,6 @@ import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandSampleProvider;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandService;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBActivitySample;
 import nodomain.freeyourgadget.gadgetbridge.model.ActivitySample;
-import nodomain.freeyourgadget.gadgetbridge.service.btle.AbstractBTLEOperation;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.TransactionBuilder;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.actions.SetDeviceBusyAction;
 import nodomain.freeyourgadget.gadgetbridge.service.devices.miband.MiBandSupport;
@@ -52,11 +51,13 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
 
     private final int activityMetadataLength = 11;
 
-    //temporary buffer, size is a multiple of 60 because we want to store complete minutes (1 minute = 3 bytes)
-    private static final int activityDataHolderSize = 3 * 60 * 4; // 4h
+    //temporary buffer, size is a multiple of 60 because we want to store complete minutes (1 minute = 3 or 4 bytes)
+    private final int activityDataHolderSize;
+    private final boolean hasExtendedActivityData;
 
     private static class ActivityStruct {
-        private final byte[] activityDataHolder = new byte[activityDataHolderSize];
+        private final byte[] activityDataHolder;
+        private final int activityDataHolderSize;
         //index of the buffer above
         private int activityDataHolderProgress = 0;
         //number of bytes we will get in a single data transfer, used as counter
@@ -68,6 +69,11 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
         //same as above, but remains untouched for the ack message
         private GregorianCalendar activityDataTimestampToAck = null;
 
+        ActivityStruct(int activityDataHolderSize) {
+            this.activityDataHolderSize = activityDataHolderSize;
+            activityDataHolder = new byte[activityDataHolderSize];
+        }
+
         public boolean hasRoomFor(byte[] value) {
             return activityDataRemainingBytes >= value.length;
         }
@@ -127,10 +133,13 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
         }
     }
 
-    private ActivityStruct activityStruct = new ActivityStruct();
+    private ActivityStruct activityStruct;
 
     public FetchActivityOperation(MiBandSupport support) {
         super(support);
+        hasExtendedActivityData = support.getDeviceInfo().isMilli1S();
+        activityDataHolderSize = getBytesPerMinuteOfActivityData() * 60 * 4; // 4h
+        activityStruct = new ActivityStruct(activityDataHolderSize);
     }
 
     @Override
@@ -208,30 +217,34 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
 
         // counter of all data held by the band
         int totalDataToRead = (value[7] & 0xff) | ((value[8] & 0xff) << 8);
-        totalDataToRead *= (dataType == MiBandService.MODE_REGULAR_DATA_LEN_MINUTE) ? 3 : 1;
+        totalDataToRead *= (dataType == MiBandService.MODE_REGULAR_DATA_LEN_MINUTE) ? getBytesPerMinuteOfActivityData() : 1;
 
 
         // counter of this data block
         int dataUntilNextHeader = (value[9] & 0xff) | ((value[10] & 0xff) << 8);
-        dataUntilNextHeader *= (dataType == MiBandService.MODE_REGULAR_DATA_LEN_MINUTE) ? 3 : 1;
+        dataUntilNextHeader *= (dataType == MiBandService.MODE_REGULAR_DATA_LEN_MINUTE) ? getBytesPerMinuteOfActivityData() : 1;
 
-        // there is a total of totalDataToRead that will come in chunks (3 bytes per minute if dataType == 1 (MiBandService.MODE_REGULAR_DATA_LEN_MINUTE)),
+        // there is a total of totalDataToRead that will come in chunks (3 or 4 bytes per minute if dataType == 1 (MiBandService.MODE_REGULAR_DATA_LEN_MINUTE)),
         // these chunks are usually 20 bytes long and grouped in blocks
         // after dataUntilNextHeader bytes we will get a new packet of 11 bytes that should be parsed
         // as we just did
 
         if (activityStruct.isFirstChunk() && dataUntilNextHeader != 0) {
             GB.toast(getContext().getString(R.string.user_feedback_miband_activity_data_transfer,
-                    DateTimeUtils.formatDurationHoursMinutes((totalDataToRead / 3), TimeUnit.MINUTES),
+                    DateTimeUtils.formatDurationHoursMinutes((totalDataToRead / getBytesPerMinuteOfActivityData()), TimeUnit.MINUTES),
                     DateFormat.getDateTimeInstance().format(timestamp.getTime())), Toast.LENGTH_LONG, GB.INFO);
         }
-        LOG.info("total data to read: " + totalDataToRead + " len: " + (totalDataToRead / 3) + " minute(s)");
-        LOG.info("data to read until next header: " + dataUntilNextHeader + " len: " + (dataUntilNextHeader / 3) + " minute(s)");
+        LOG.info("total data to read: " + totalDataToRead + " len: " + (totalDataToRead / getBytesPerMinuteOfActivityData()) + " minute(s)");
+        LOG.info("data to read until next header: " + dataUntilNextHeader + " len: " + (dataUntilNextHeader / getBytesPerMinuteOfActivityData()) + " minute(s)");
         LOG.info("TIMESTAMP: " + DateFormat.getDateTimeInstance().format(timestamp.getTime()) + " magic byte: " + dataUntilNextHeader);
 
         activityStruct.startNewBlock(timestamp, dataUntilNextHeader);
     }
 
+    private int getBytesPerMinuteOfActivityData() {
+        return hasExtendedActivityData ? 4 : 3;
+    }
+
     /**
      * Method to store temporarily the activity data values got from the Mi Band.
      * <p/>
@@ -290,7 +303,8 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
             LOG.debug("nothing to flush, struct is already null");
             return;
         }
-        LOG.debug("flushing activity data samples: " + activityStruct.activityDataHolderProgress / 3);
+        int bpm = getBytesPerMinuteOfActivityData();
+        LOG.debug("flushing activity data samples: " + activityStruct.activityDataHolderProgress / bpm);
         byte category, intensity, steps;
 
         DBHandler dbHandler = null;
@@ -299,18 +313,19 @@ public class FetchActivityOperation extends AbstractMiBandOperation {
             int minutes = 0;
             try (SQLiteDatabase db = dbHandler.getWritableDatabase()) { // explicitly keep the db open while looping over the samples
                 int timestampInSeconds = (int) (activityStruct.activityDataTimestampProgress.getTimeInMillis() / 1000);
-                if ((activityStruct.activityDataHolderProgress % 3) != 0) {
-                    throw new IllegalStateException("Unexpected data, progress should be mutiple of 3: " + activityStruct.activityDataHolderProgress);
+                if ((activityStruct.activityDataHolderProgress % bpm) != 0) {
+                    throw new IllegalStateException("Unexpected data, progress should be mutiple of " + bpm +": " + activityStruct.activityDataHolderProgress);
                 }
-                int numSamples = activityStruct.activityDataHolderProgress/3;
+                int numSamples = activityStruct.activityDataHolderProgress / bpm;
                 ActivitySample[] samples = new ActivitySample[numSamples];
                 SampleProvider sampleProvider = new MiBandSampleProvider();
                 int s = 0;
 
-                for (int i = 0; i < activityStruct.activityDataHolderProgress; i += 3) {
+                for (int i = 0; i < activityStruct.activityDataHolderProgress; i += bpm) {
                     category = activityStruct.activityDataHolder[i];
                     intensity = activityStruct.activityDataHolder[i + 1];
                     steps = activityStruct.activityDataHolder[i + 2];
+                    byte unknown = activityStruct.activityDataHolder[i + 3];
 
                     samples[minutes] = new GBActivitySample(
                             sampleProvider,