diff --git a/DetectorDescription/GeoModel/GeoModelSvc/src/GeoModelSvc.cxx b/DetectorDescription/GeoModel/GeoModelSvc/src/GeoModelSvc.cxx
index a1bf57b7f50e2ccf84714e96ae86b600c32ba46e..6ba2dbc0b121bbe71ad364a51d2d843533ef4b5c 100644
--- a/DetectorDescription/GeoModel/GeoModelSvc/src/GeoModelSvc.cxx
+++ b/DetectorDescription/GeoModel/GeoModelSvc/src/GeoModelSvc.cxx
@@ -281,7 +281,7 @@ StatusCode GeoModelSvc::geoInit()
 
   // Build the world node from which everything else will be suspended
   const GeoMaterial* air = theMaterialManager->getMaterial("std::Air");  
-  const GeoBox* worldBox = new GeoBox(1000*Gaudi::Units::cm,1000*Gaudi::Units::cm, 1000*Gaudi::Units::cm);
+  const GeoBox* worldBox = new GeoBox(6000*Gaudi::Units::cm,2500*Gaudi::Units::cm, 12000*Gaudi::Units::cm);
   const GeoLogVol* worldLog = new GeoLogVol("WorldLog", worldBox, air);
   GeoPhysVol *worldPhys=new GeoPhysVol(worldLog);
   
diff --git a/Simulation/G4Faser/G4FaserTools/python/G4GeometryToolConfig.py b/Simulation/G4Faser/G4FaserTools/python/G4GeometryToolConfig.py
index 4e6f59490a97baee0020453bb9572fab2b090fbc..a98b46638f7595405208e4b8932295c606360fb0 100644
--- a/Simulation/G4Faser/G4FaserTools/python/G4GeometryToolConfig.py
+++ b/Simulation/G4Faser/G4FaserTools/python/G4GeometryToolConfig.py
@@ -180,9 +180,9 @@ def FASEREnvelopeCfg(ConfigFlags, name="Faser", **kwargs):
     kwargs.setdefault("OffsetX", 0.0 * mm)
     kwargs.setdefault("OffsetY", 0.0 * mm)
     kwargs.setdefault("OffsetZ", 0.0 * mm)
-    kwargs.setdefault("dX", 600.0 * mm) 
-    kwargs.setdefault("dY", 600.0 * mm) 
-    kwargs.setdefault("dZ", 4000.0 * mm) 
+    kwargs.setdefault("dX", 6000.0 * mm) 
+    kwargs.setdefault("dY", 2500.0 * mm) 
+    kwargs.setdefault("dZ", 12000.0 * mm) 
 
     kwargs.setdefault("DetectorName", "Faser")
     SubDetectorList = result.popToolsAndMerge(generateSubDetectorList(ConfigFlags))