ST5 Adjustable Top Air System 4 Pack As you can see the

As you can see the most likely choice would be #3

Comes in a pair (driver and passenger side)

24 green outer LEDs for quick reference to engine parameter

Widest length 85mm (left to right inside of teardrop)

Machined O-ring receiver grooves on the end caps ensure against leaks

ST5 Adjustable Top Air System 4 Pack As you can see theAdjustable top air system for Stilo ST5 helmets Fits helmet sizes L 60 to XXL 64 Features: The Stilo Top Air System is designed for use with any Stilo ST5 helmet fitted with a full visor The exclusive system takes fresh air to the driver's head and nose With the innovative system for airflow regulation, you can favor the airflow on the driver for facial airflow or cool the driver's head Thanks to the fixation system you can fit the Top Air System more