diff --git a/Mu2eG4/geom/geom_run2.txt b/Mu2eG4/geom/geom_run2.txt
index c49cedf434..bab52ace3f 100644
--- a/Mu2eG4/geom/geom_run2.txt
+++ b/Mu2eG4/geom/geom_run2.txt
@@ -60,7 +60,7 @@ double mu2e.detectorSystemZ0 = 10171.;   // mm  G4BL: (17730-7292=9801 mm)
 #include "Offline/Mu2eG4/geom/TSdA_v02.txt"
 #include "Offline/Mu2eG4/geom/muonBeamStop_v08.txt"
 
-#include "Offline/Mu2eG4/geom/STM_v10.txt" // (muon) stopping target monitor
+#include "Offline/Mu2eG4/geom/STM_v09.txt" // (muon) stopping target monitor
 
 // Proton Absorber
 #include "Offline/Mu2eG4/geom/protonAbsorber_cylindrical_v04.txt"
diff --git a/Mu2eG4/geom/protonAbsorber_cylindrical_v04.txt b/Mu2eG4/geom/protonAbsorber_cylindrical_v04.txt
index 4cedf0fa6e..ca1ec36d62 100644
--- a/Mu2eG4/geom/protonAbsorber_cylindrical_v04.txt
+++ b/Mu2eG4/geom/protonAbsorber_cylindrical_v04.txt
@@ -64,7 +64,7 @@ double protonabsorber.outerPAslotOffset         = -410.0; // mm - relative
 
 // oPA Supports are Aluminum rings that support and "hold together" the
 // OPA.  Support rings and bars for the IPA are also included here
-string protonabsorber.oPASupportMaterialName = "StainlessSteel316";
+string protonabsorber.oPASupportMaterialName = "Al6061";
 int    protonabsorber.oPASupportNSupportRing = 6;
 vector<double> protonabsorber.oPASupportInnerRadii = {506.3, 564.4, 665.0, 662.  , 721.  , 665.0}; //index 2 and 5 are 378.4 mm + 2*half lengths apart
 vector<double> protonabsorber.oPASupportOuterRadii = {606.3, 714.4, 685.0, 761.25, 819.35, 685.0};
@@ -80,18 +80,18 @@ double  protonabsorber.oPASupportSlatHeight = 20.0; // mm
 double  protonabsorber.oPASupportSlatWidth  = 50.0; // mm
 double  protonabsorber.oPASupportSlatLength = 800.0; // mm - Same as ST
 
-vector<string> protonabsorber.oPASupportMaterials = { "StainlessSteel316"
-                                                      ,"StainlessSteel316"
-                                                      ,"StainlessSteel316"
-                                                      ,"StainlessSteel316"
-                                                      ,"StainlessSteel316"
-                                                      ,"StainlessSteel316"};
+vector<string> protonabsorber.oPASupportMaterials = { "Al6061"
+                                                      ,"Al6061"
+                                                      ,"Al6061"
+                                                      ,"Al6061"
+                                                      ,"Al6061"
+                                                      ,"Al6061"};
 //slats for the stopping target supports
 int            protonabsorber.nOPASupportSlats             = 3;
 vector<double> protonabsorber.oPASupportSlatAngles         = {0.,120.,240.}; // degrees
 vector<int>    protonabsorber.oPASupportSlatTypes          = {0 ,  1 ,  0 };
 int            protonabsorber.nOPASupportSlatTypes         = 2;
-vector<string> protonabsorber.oPASupportSlatMaterials      = { "StainlessSteel316", "StainlessSteel316"};
+vector<string> protonabsorber.oPASupportSlatMaterials      = { "Al6061", "Al6061"};
 vector<string> protonabsorber.oPASupportSlatFillMaterials  = { "BronzeC642"       , "G4_Al"            };
 vector<double> protonabsorber.oPASupportSlatHeights        = {  45. ,   40.  }; // mm
 vector<double> protonabsorber.oPASupportSlatWidths         = {  127.,   35.  }; // mm
@@ -122,7 +122,7 @@ vector<int>    protonabsorber.crossSupportTwoIndex    = {  5   ,  5   ,  5   };
 vector<double> protonabsorber.crossSupportPhis        = { -20.  ,100.  ,220.  }; //phi about ring
 vector<double> protonabsorber.crossSupportHeights     = {228.6 ,228.6 ,228.6 }; //height of box, width of box from ring separation
 vector<double> protonabsorber.crossSupportRadii       = {665.  ,665.  ,665.  }; //radius of the support center
-string         protonabsorber.crossSupportMaterial    = "StainlessSteel316";
+string         protonabsorber.crossSupportMaterial    = "Al6061";
 
 
 // This tells emacs to view this file in c++ mode.