diff --git a/src/toolbox_scs/constants.py b/src/toolbox_scs/constants.py
index ba0945c5cfe239c109fb5cc6ec187a9a6264615a..d9a4639f8d2603cca90c29e596b31a460cd888d2 100644
--- a/src/toolbox_scs/constants.py
+++ b/src/toolbox_scs/constants.py
@@ -156,6 +156,9 @@ mnemonics = {
     "MAG_CHICANE_DELAY": ({'source': 'SA3_XTD4_CHICANE/DOOCS/SXR2CPP',
                            'key': 'XFEL_MAGNETS_CHICANE_SXR2CPP.dtFs.value',
                            'dim': None},),
+    "Pol": ({'source': 'SA3_XTD10_UND/DOOCS/PHOTON_ENERGY',
+             'key': 'actualPolarization.value',
+              'dim': None},),
 
     # PES
     "PES_1Araw": ({'source': 'SA3_XTD10_PES/ADC/1:network',