diff --git a/apps/counter/models.py b/apps/counter/models.py
index ca74911..ff1f22e 100644
--- a/apps/counter/models.py
+++ b/apps/counter/models.py
@@ -26,7 +26,7 @@ class DeviceCount(models.Model):
         verbose_name_plural = verbose_name
 
     def __str__(self):
-        return self.device_id
+        return '{0} at {1}'.format(self.device_id, self.data_time)
 
 
 class DeviceInfo(models.Model):