diff --git a/devices/slit1H neg blade.properties b/devices/slit1H neg blade.properties
index 00f3958..a42c363 100644
--- a/devices/slit1H neg blade.properties	
+++ b/devices/slit1H neg blade.properties	
@@ -6,7 +6,7 @@ maxValue=NaN
 minSpeed=0.001
 minValue=NaN
 offset=0.0
-precision=-1
+precision=3
 resolution=NaN
 scale=1.0
-unit=null
+unit=mm
diff --git a/devices/slit1H pos blade.properties b/devices/slit1H pos blade.properties
index 00f3958..a42c363 100644
--- a/devices/slit1H pos blade.properties	
+++ b/devices/slit1H pos blade.properties	
@@ -6,7 +6,7 @@ maxValue=NaN
 minSpeed=0.001
 minValue=NaN
 offset=0.0
-precision=-1
+precision=3
 resolution=NaN
 scale=1.0
-unit=null
+unit=mm
diff --git a/devices/slit1V neg blade.properties b/devices/slit1V neg blade.properties
index 00f3958..a42c363 100644
--- a/devices/slit1V neg blade.properties	
+++ b/devices/slit1V neg blade.properties	
@@ -6,7 +6,7 @@ maxValue=NaN
 minSpeed=0.001
 minValue=NaN
 offset=0.0
-precision=-1
+precision=3
 resolution=NaN
 scale=1.0
-unit=null
+unit=mm
diff --git a/devices/slit1V pos blade.properties b/devices/slit1V pos blade.properties
index 00f3958..a42c363 100644
--- a/devices/slit1V pos blade.properties	
+++ b/devices/slit1V pos blade.properties	
@@ -6,7 +6,7 @@ maxValue=NaN
 minSpeed=0.001
 minValue=NaN
 offset=0.0
-precision=-1
+precision=3
 resolution=NaN
 scale=1.0
-unit=null
+unit=mm