diff --git a/libp2p/stream_muxer/mplex/datastructures.py b/libp2p/stream_muxer/mplex/datastructures.py
new file mode 100644
index 0000000..28a4b41
--- /dev/null
+++ b/libp2p/stream_muxer/mplex/datastructures.py
@@ -0,0 +1,6 @@
+from typing import NamedTuple
+
+
+class StreamID(NamedTuple):
+    channel_id: int
+    is_initiator: bool