Amazon.com: BoxWave Stylus Pen Compatible with Lenovo Chromebook Duet (Stylus Pen by BoxWave) - AccuPoint Active Stylus, Electronic Stylus with Ultra Fine Tip for Lenovo Chromebook Duet - Metallic Silver : Electronics
Amazon.com: Lenovo USI Stylus Pen, Chrome OS Support, 4,096 Levels of Pressure Sensitivity, 150 Days Battery Life, AAAA Battery, Works with Chromebook, GX81B10212 : Everything Else
Amazon.com: tesha USI Stylus Pen for Chromebook with 4096 Levels Pressure for Lenovo Chromebook Duet, Chromebook C436/C536/CM5/CX5, HP Chromebook X360 12b/14b/11a, Including AAAA Battery & Spare Tip : Electronics
Another mod for Lenovo Duet w/USI pen storage : r/chromeos
Lenovo Chromebook Duet | 2 in 1 Chromebook | Lenovo US
PenTex USI Stylus for Chromebook with Touchscreen | Active Digital Pen Compatible with LENOVO Duet &
Lenovo USI Pen vs. HP USI Pen: Which one is better? (IdeaPad Duet Chromebook) - YouTube
Here's How the Duet 5's Pen Looks Like | onchrome
For $38, you can buy the USI stylus designed for the Lenovo Chromebook Duet
Lenovo Chromebook Duet Review | PCMag
A new rechargeable USI stylus from Broonel has hit the market
Lenovo Duet Chromebook: HP USI Stylus & Pen Features Tested - YouTube
Lenovo USI Pen is now available for $40 - 9to5Google