The AHD Air Forced Gen II unit is designed and manufactured by Antman Helmet Design. This low profile unit offers an alternative to your brand bought air intake, it's sleeker, more precise design will give you maximum air. The Gen II is designed to suit most BELL helmets, and Stilo ST4 helmets. Includes double sided tape for assembly.* Hose connector sold separately.* Please indicate if you want a 20mm or 25mm round hole cut to house your air feed.