Bluetooth Dual Button-Box
These 3 devices all use my BSI internally. So sometimes I refer to the BSI *inside* the BDBB and other times, when I feel it's important to know which device to focus on, I refer to the BDBB. All of these devices provide access to 'switch-friendly' apps specifically programmed to work with switch(es). They can also be configured to work with several non-switch-friendly apps (Music, Camera, and some e-book apps). In addition, they work with iOS 7's Switch Control when configured for either 1 switch Autoscan or 2 switch Step-Scan.
More information: http://www.rjcooper.com/bluetooth-dual-button-box/index.html