diff --git a/columbus/env.py b/columbus/env.py
index 28fcfc3..2e09ad7 100644
--- a/columbus/env.py
+++ b/columbus/env.py
@@ -513,7 +513,7 @@ class ColumbusConfigDefined(ColumbusEnv):
         if s.replace('.', '', 1).isdigit():
             return True
         num, unit = s[:-2], s[-2:]
-        if unit in ['px', 'em', 'rx', 'ry', 'ct']:
+        if unit in ['px', 'em', 'rx', 'ry', 'ct', 'au']:
             if num.replace('.', '', 1).isdigit():
                 return True
         return False
@@ -538,6 +538,8 @@ class ColumbusConfigDefined(ColumbusEnv):
             em = num
         elif unit == 'px':
             em = num / ({'x': self.width, 'y': self.height}[axis])
+        elif unit == 'au':
+            em = num * 36 / ({'x': self.width, 'y': self.height}[axis])
         elif unit == 'ct':
             em = num / 100
         else:
diff --git a/configs/Example_Units.yaml b/configs/Example_Units.yaml
index 4499b74..c5ba7d7 100644
--- a/configs/Example_Units.yaml
+++ b/configs/Example_Units.yaml
@@ -6,13 +6,15 @@ name: "DEFAULT"
 # ct: 100ct = Full Width / Height
 # rx: pixels relative to width
 # ry: pixels relative to height
+# au: 1au = 36px
 #
 # When no unit is given, we use the folowing defaults
 # (compatible with legacy behavior)
 # pos: em
 # all other: px
 #
-# ct is the recommendet unit...
+# ct is the recommendet unit.
+# If you need a unit, that is not responsive in regards to width/height, use au / px.
 
 params:
   task:
@@ -70,7 +72,7 @@ params:
           pos: [0.75em, 90px]
         - type: OnceReward
           reward: 100
-          radius: 3ct
+          radius: 1au
           pos: [0.3, 0.8] # defaults to em
       start_pos: [90ct, 20ct]
       default_collision_elasticity: 0.8