Bean Pod 2 Pk: Universal Nike+ iPod Sensor Holder - Nike Plus iPod Sensor Cases, Works w/ All Shoes: 1 Red Sensor Shoe Pouch and 1 Blue Sensor Shoe Pouch (B001M5QUPG)
Nike Makes Elite Training Available for All Using a Sensor Technology — POPSOP
Create Your Own Nike+ (Nike Plus) Sensor Hole in Your Running Shoes : 4 Steps - Instructables
How Do I Insert the Nike Plus Sensor Into My Shoe?