diff --git a/Ploopy-Mini-Trackball-Kit-Assembly.md b/Ploopy-Mini-Trackball-Kit-Assembly.md
index 7b745b8..f10e1da 100644
--- a/Ploopy-Mini-Trackball-Kit-Assembly.md
+++ b/Ploopy-Mini-Trackball-Kit-Assembly.md
@@ -207,9 +207,14 @@ Prepare the following components:
 
 - Base
 - Top
+- ADNS-5050 sensor optic
 - 4x screw
 - 4x friction pads
 
+## Step X: Place ADNS-5050 sensor optic on printed circuit board
+
+**TODO photo of sensor optic placed down
+
 ## Step X: Place top onto base
 
 **TODO photo of top placed onto base**