diff --git a/extensions/fablabchemnitz/bounding_box/bounding_box.inx b/extensions/fablabchemnitz/bounding_box/bounding_box.inx
index 38ecee40..5cbe9501 100644
--- a/extensions/fablabchemnitz/bounding_box/bounding_box.inx
+++ b/extensions/fablabchemnitz/bounding_box/bounding_box.inx
@@ -3,10 +3,20 @@
     <name>Bounding Box</name>
     <id>fablabchemnitz.de.bounding_box</id>
     <label>Draws bounding boxes around selected objects, useful for debugging. Author: Pawel Mosakowski. Modded by Mario Voigt.</label>
+    <param name="unit" gui-text="Unit" type="optiongroup" appearance="combo" gui-description="The unit applies to interval and thresholds">
+        <option value="mm">mm</option>
+        <option value="cm">cm</option>
+        <option value="px">px</option>
+        <option value="pt">pt</option>
+        <option value="pc">pc</option>
+        <option value="in">in</option>
+    </param>
     <param name="offset" min="-10000.000" max="10000.000" precision="3" type="float" gui-text="Offset from object (all directions)">0.000</param>
-    <param name="box" type="bool" gui-text="Draw boxes">true</param>
     <param name="corner_radius" type="float" min="0.000" precision="3" max="10000.000" gui-text="Corner radius" gui-description="Only applies for box type">0.000</param>
+    <separator/>
+    <param name="box" type="bool" gui-text="Draw boxes">true</param>
     <param name="circle" type="bool" gui-text="Draw circles">false</param>
+    <separator/>
     <param name="split" type="bool" gui-text="Handle selection as group">true</param>
     <effect>
         <object-type>all</object-type>
diff --git a/extensions/fablabchemnitz/bounding_box/bounding_box.py b/extensions/fablabchemnitz/bounding_box/bounding_box.py
index e41bcaff..7dafd727 100644
--- a/extensions/fablabchemnitz/bounding_box/bounding_box.py
+++ b/extensions/fablabchemnitz/bounding_box/bounding_box.py
@@ -8,19 +8,22 @@ class BoundingBox(inkex.EffectExtension):
     
     def add_arguments(self, pars):
         pars.add_argument('--offset', type=float, default=0.0, help='Offset from object (all directions)')
+        pars.add_argument('--unit', default="mm")
         pars.add_argument('--box', type=inkex.Boolean, default=0.0, help='Draw boxes')
         pars.add_argument('--corner_radius', type=float, default=0.0, help='Corner radius')
         pars.add_argument('--circle', type=inkex.Boolean, default=0.0, help='Draw circles')
         pars.add_argument('--split', type = inkex.Boolean, default = True, help = 'Handle selection as group')
       
     def drawBBox(self, bbox):
+        so = self.options
+        offset = self.svg.unittouu(str(so.offset) + so.unit)
         if self.options.box:
             attribs = {
-                'style' : str(inkex.Style({'stroke':'#ff0000','stroke-width'  : '1','fill':'none'})),
-                'x'     : str(bbox.left - self.options.offset),
-                'y'     : str(bbox.top - self.options.offset),
-                'width' : str(bbox.width + 2 * self.options.offset),
-                'height': str(bbox.height + 2 * self.options.offset),
+                'style' : str(inkex.Style({'stroke':'#ff0000','stroke-width':str(self.svg.unittouu("1px")),'fill':'none'})),
+                'x'     : str(bbox.left - offset),
+                'y'     : str(bbox.top - offset),
+                'width' : str(bbox.width + 2 * offset),
+                'height': str(bbox.height + 2 * offset),
                 'ry'    : str(self.options.corner_radius),
                 'rx'    : str(self.options.corner_radius)
             }
@@ -28,23 +31,42 @@ class BoundingBox(inkex.EffectExtension):
 		    	
         if self.options.circle:			    	
             attribs = {
-                'style': str(inkex.Style({'stroke':'#ff0000','stroke-width'  : '1','fill':'none'})),
+                'style': str(inkex.Style({'stroke':'#ff0000','stroke-width':str(self.svg.unittouu("1px")),'fill':'none'})),
                 'cx'   : str(bbox.center_x),
                 'cy'   : str(bbox.center_y),
-                #'r'   : str(bbox.width / 2 + self.options.offset),
-                'r'    : str(math.sqrt((bbox.width + 2 * self.options.offset)* (bbox.width + 2 * self.options.offset) + (bbox.height + 2 * self.options.offset) * (bbox.height + 2 * self.options.offset)) / 2),
+                #'r'   : str(bbox.width / 2 + offset),
+                'r'    : str(math.sqrt((bbox.width + 2 * offset)* (bbox.width + 2 * offset) + (bbox.height + 2 * self.options.offset) * (bbox.height + 2 * self.options.offset)) / 2),
             }
             etree.SubElement(self.svg.get_current_layer(), inkex.addNS('circle','svg'), attribs)
+     
       
     def effect(self):
+        
+        scale_factor = self.svg.unittouu("1px")
+        
         if len(self.svg.selected) > 0:
             if self.options.split is False:
                 for element in self.svg.selected.values():
-                    self.drawBBox(element.bounding_box())
-            else:
+                    if isinstance (element, inkex.ShapeElement) and element.tag != inkex.addNS('use','svg') and element.get('inkscape:groupmode') != 'layer': #bbox fails for svg:use elements and layers:
+                        if isinstance (element, inkex.Rectangle) or \
+                           isinstance (element, inkex.Circle) or \
+                           isinstance (element, inkex.Ellipse):
+                                self.drawBBox(element.bounding_box() * scale_factor)
+                        else:
+                            self.drawBBox(element.bounding_box())
+            else: #combined bbox
                 #self.drawBBox(self.svg.get_selected_bbox()) #works for InkScape (1:1.0+devel+202008292235+eff2292935) @ Linux and for Windows (but with deprecation)
-                self.drawBBox(self.svg.selection.bounding_box()) #works for InkScape 1.1dev (9b1fc87, 2020-08-27)) @ Windows
-
+                #self.drawBBox(self.svg.selection.bounding_box()) #works for InkScape 1.1dev (9b1fc87, 2020-08-27)) @ Windows
+                bbox = inkex.BoundingBox()
+                for element in self.svg.selected.values():
+                    if isinstance (element, inkex.ShapeElement) and element.tag != inkex.addNS('use','svg') and element.get('inkscape:groupmode') != 'layer': #bbox fails for svg:use elements and layers:
+                        if isinstance (element, inkex.Rectangle) or \
+                           isinstance (element, inkex.Circle) or \
+                           isinstance (element, inkex.Ellipse):
+                                bbox += element.bounding_box() * scale_factor
+                        else:
+                            bbox += element.bounding_box()
+                self.drawBBox(bbox)       
         else:
             inkex.errormsg('Please select some objects first.')
             return