diff --git a/src/pg_rad/isotopes/__init__.py b/src/pg_rad/isotopes/__init__.py
index 0c7976d..6f000c0 100644
--- a/src/pg_rad/isotopes/__init__.py
+++ b/src/pg_rad/isotopes/__init__.py
@@ -2,7 +2,9 @@
 __ignore__ = ["logger"]
 
 from pg_rad.isotopes import isotope
+from pg_rad.isotopes import presets
 
 from pg_rad.isotopes.isotope import (Isotope,)
+from pg_rad.isotopes.presets import (CS137,)
 
-__all__ = ['Isotope', 'isotope']
+__all__ = ['CS137', 'Isotope', 'isotope', 'presets']