diff --git a/lib/ansible/modules/cloud/rackspace/rax_cbs_attachments.py b/lib/ansible/modules/cloud/rackspace/rax_cbs_attachments.py
index 74e4dac670..9193ae0acc 100644
--- a/lib/ansible/modules/cloud/rackspace/rax_cbs_attachments.py
+++ b/lib/ansible/modules/cloud/rackspace/rax_cbs_attachments.py
@@ -31,7 +31,8 @@ version_added: 1.6
 options:
   device:
     description:
-      - The device path to attach the volume to, e.g. /dev/xvde
+      - The device path to attach the volume to, e.g. /dev/xvde.
+      - Before 2.4 this was a required field. Now it can be left to null to auto assign the device name.
     default: null
     required: false
   volume: