Yet another hint about the impending launch of the Steam Frame VR headset has emerged, thanks to a new FCC filing showing details of the battery systems used by both the headset and its controllers. Along with the controllers shown using standard AA batteries, the filing also contains details about a hot-swappable battery system available in a mystery "Frame Enthusiast kit." With the Steam Frame set to be competing for the crown of 'best VR headset' once it launches at some point this summer, any hints as to its price and release date are like gold dust to prospective buyers, and this latest filing is among the strongest hints yet of just how soon it will arrive. It's set to launch around the same time as the Steam Machine release date, but the exact launch dates of both devices are still to be nailed down.