diff --git a/readme.md b/readme.md
index 583e1ed..d9040ca 100644
--- a/readme.md
+++ b/readme.md
@@ -1524,6 +1524,7 @@ E.g. a "brown" socket for mains live needs to be displayed as "sienna" to look r
 |:--- |:--- |
 | `jack_4mm_hole_radius()` | Panel hole radius for 4mm jack |
 | `jack_4mm_shielded_hole_radius()` | Panel hole radius for 4mm shielded jack |
+| `jack_4mm_shielded_nut_radius()` | Largest diameter of 4mm shielded jack |
 | `post_4mm_diameter()` | Outer diameter of 4mm binding post |
 
 ### Modules
diff --git a/vitamins/jack.scad b/vitamins/jack.scad
index 4b880cc..dbda9b3 100644
--- a/vitamins/jack.scad
+++ b/vitamins/jack.scad
@@ -87,7 +87,8 @@ module jack_4mm(colour, thickness, display_colour = false) { //! Draw a 4mm jack
             }
 }
 
-function jack_4mm_shielded_hole_radius() = 12/2; //! Panel hole radius for 4mm shielded jack
+function jack_4mm_shielded_hole_radius() = 12 / 2; //! Panel hole radius for 4mm shielded jack
+function jack_4mm_shielded_nut_radius() = 14.4 / 2; //! Largest diameter of 4mm shielded jack
 
 module jack_4mm_shielded(colour, thickness, display_colour = false) { //! Draw a 4mm shielded jack
     vitamin(str("jack_4mm_shielded(\"", colour, "\", 3", arg(display_colour, false), "): 4mm shielded jack socket ", colour));