diff --git a/src/scgenerator/parameter.py b/src/scgenerator/parameter.py
index a8ed59b..4649b12 100644
--- a/src/scgenerator/parameter.py
+++ b/src/scgenerator/parameter.py
@@ -311,7 +311,7 @@ class Parameters:
     name: str = Parameter(string)
 
     # fiber
-    input_transmission: float = Parameter(in_range_incl(0, 1), default=1.0)
+    input_transmission: float = Parameter(in_range_incl(0, 1), default=1.0, unit="%")
     gamma: float = Parameter(non_negative(*number))
     n2: float = Parameter(non_negative(*number))
     chi3: float = Parameter(non_negative(*number))