diff --git a/torsen.scad b/torsen.scad
index 68f9df0..3fb53ff 100644
--- a/torsen.scad
+++ b/torsen.scad
@@ -1,3 +1,10 @@
+// LEGO-compatible self-locking Torsen-like differential housing
+// With either double-bevel or single-bevel 36t gear
+// (c) Vitaliy Filippov 2015
+// License: GNU GPL 3.0 or later
+
+// How to use it - see http://www.thingiverse.com/thing:1236953
+
 $fn = 100;
 
 torsen_diff_36t();