Disc Brake Dual Control Lever (Wireless)
The 105 ST-7170 Hydraulic Disc Brake levers weigh about 211 per lever.
Unlike its sibling 12-speed shifters (ST-R9270/ST-R8170), these 105 levers do not have 'hidden' hood buttons. They also don't have a satellite shifter port.
They do however support wireless shifting, and take two CR1632 batteries per lever. Also, the single E-Tube port (SD300 type) can be used to update and troubleshoot the levers, or wire them to the rest of the system.
Alternatives - compatibility
Let's say you just bought a 105 Di2 bike, but really want the hood buttons or the ability to connect satellite shifters (SW-RS801-T/SW-RS801-S).
These shift levers don't support either of those, but don't worry - 105 Di2 (R7150) is fully compatible with the DURA-ACE and Ultegra 12-speed groupsets. You could upgrade the levers to (ST-R9270/ST-R8170), while keeping the other components at 105 level.