There's been a lot of talk about the Team Wendy helmets and their various features. Here's a shot of the EXFIL from Team Wendy of the T-slots on the EXFIL with a wide variety of hardware fasteners and screws attached.
"We designed the T-slots on the EXFIL to allow for easy attachment of nearly any accessory. We have been collecting and trialing various fasteners available from any hardware store. The picture shows our EXFIL with everything from a snap and retention bolt to a nylon screw. Happy fastening!!!" Team Wendy