diff --git a/src/legendoptics/data/pen_abslength.dat b/src/legendoptics/data/pen_abslength.dat
index 6dd5587..40e1f1a 100644
--- a/src/legendoptics/data/pen_abslength.dat
+++ b/src/legendoptics/data/pen_abslength.dat
@@ -1,4 +1,4 @@
-# nm     cm
+# nm     mm
 380.5359 0.3758
 382.7277 0.4457
 384.6675 0.5604
diff --git a/src/legendoptics/pen.py b/src/legendoptics/pen.py
index 75b809f..5d389b8 100644
--- a/src/legendoptics/pen.py
+++ b/src/legendoptics/pen.py
@@ -93,7 +93,7 @@ def pen_wls_absorption() -> tuple[Quantity, Quantity]:
     .. optics-plot:: {'yscale': 'log'}
     """
     wvl = np.array([70, 71, 380, 381]) * u.nm
-    absorp = np.array([1e3, 2e-4, 2e-4, 1e3]) * u.m  # 1e3 is "infinity"
+    absorp = np.array([1e3, 2e-8, 2e-8, 1e3]) * u.m  # 1e3 is "infinity"
     assert absorp.check("[length]")
     return wvl, absorp