diff --git a/docs/pages/api-reference.md b/docs/pages/api-reference.md
index b610009..636f9a2 100644
--- a/docs/pages/api-reference.md
+++ b/docs/pages/api-reference.md
@@ -313,6 +313,36 @@ Loads the output of Proffast 2 into a polars DataFrame.
   A polars DataFrame containing all columns.
 
 
+##### `SERIAL_NUMBERS`
+
+The serial numbers of the EM27 devices.
+
+
+##### `COLORS`
+
+Colors recommended for plotting the EM27 data.
+
+
+##### `COLORS_LIGHT`
+
+Lighter colors recommended for plotting the EM27 data.
+
+
+##### `COLORS_DARK`
+
+Darker colors recommended for plotting the EM27 data.
+
+
+##### `PROFFAST_MULTIPLIERS`
+
+Multiplication factors for the EM27 data retrieved using Proffast to bring the data in a common unit.
+
+
+##### `PROFFAST_UNITS`
+
+Units for the EM27 data retrieved using Proffast after applying the multiplication factor.
+
+
 ## `tum_esm_utils.files`
 
 File-related utility functions.
diff --git a/tum_esm_utils/em27.py b/tum_esm_utils/em27.py
index 8d316a2..255c770 100644
--- a/tum_esm_utils/em27.py
+++ b/tum_esm_utils/em27.py
@@ -258,6 +258,8 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "me": 117,
     "kc": 83,
 }
+"""The serial numbers of the EM27 devices."""
+
 COLORS: dict[str, str] = {
     "ma": TCH.YELLOW_500,
     "mb": TCH.ORANGE_500,
@@ -266,6 +268,8 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "me": TCH.BLUE_500,
     "kc": TCH.GREEN_500,
 }
+"""Colors recommended for plotting the EM27 data."""
+
 COLORS_LIGHT: dict[str, str] = {
     "ma": TCH.YELLOW_400,
     "mb": TCH.ORANGE_400,
@@ -274,6 +278,8 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "me": TCH.BLUE_400,
     "kc": TCH.GREEN_400,
 }
+"""Lighter colors recommended for plotting the EM27 data."""
+
 COLORS_DARK: dict[str, str] = {
     "ma": TCH.YELLOW_600,
     "mb": TCH.ORANGE_600,
@@ -282,7 +288,9 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "me": TCH.BLUE_600,
     "kc": TCH.GREEN_600,
 }
-MULTIPLIERS: dict[str, float] = {
+"""Darker colors recommended for plotting the EM27 data."""
+
+PROFFAST_MULTIPLIERS: dict[str, float] = {
     "XCO2": 1,
     "XCH4": 1000,
     "XCO": 1000,
@@ -302,7 +310,9 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "CO": 1 / (6.022 * 10e+23),
     "CH4_S5P": 1 / (6.022 * 10e+23),
 }
-UNITS: dict[str, str] = {
+"""Multiplication factors for the EM27 data retrieved using Proffast to bring the data in a common unit."""
+
+PROFFAST_UNITS: dict[str, str] = {
     "XH2O": "ppm",
     "XAIR": "ppm",
     "XCO2": "ppm",
@@ -318,3 +328,4 @@ def load_proffast2_result(path: str) -> pl.DataFrame:
     "CO": "mol",
     "CH4_S5P": "mol",
 }
+"""Units for the EM27 data retrieved using Proffast after applying the multiplication factor."""