Bit more information for everyone on the mindwave mobile/mobile+/mobile 2 and the myndplay myndband and BLE.
I think all of these TGAM-based wireless headsets with BLE use the Silicon Labs BT121 module.
The non-BLE bluetooth SPP on these sends raw TGAM data collected at 56Kbit. This data corresponds to the protocol implemented by the Brain module in Espruino.
However, the BLE characteristics don't seem to implement raw data transmission, even though a characteristic (039afff4-2c94-11e3-9e06-0002a5d5c51b) is definied for raw EEG data. The 039afff8-2c94-11e3-9e06-0002a5d5c51b characteristic does not send data in any publicly-documented format. I believe it's a series of integers representing the computed values generated by TGAM (poor signal, EEG power bands, attention and meditation values), but the exact data breakdown is not clear. I can't even find the poor signal quality signal value.
Basically, I think these headsets are not useable from Bangle.js unless somebody reflashes the BT121 firmware to support raw data transmission. That should be feasible, but rather alot of work unless NeuroSky would be willing to release the original BT121 project files.