TT / Triathlon Dual Control Lever
The TT/Triathlon DUAL CONTROL LEVER (2x11-speed) is available for both the left and the right and weighs about 127g/pair.
These shifters can only be used with Synchronized Shift. They only have one button each, so you generally set one up to shift the RD to an easier gear and the other to shift to a harder gear.
Using Synchro Shift would make the bike shift the front derailleur automatically, so not being able to shift the FD using a button or shifter is no problem.
These TT/Triathlon shift levers are 12-speed compatible, if you update them to firmware version 3.3.0 or newer.
In order to update these shifters, either connect them to the SM-PCE02 or SM-PCE1 on their own, or connect them to an 11-speed Di2 bike and use the SM-BCR2 charger to run the firmware update.
These shifters have to be connected to the BT-DN300 battery by wire. They will not function if there isn't a wired connection between them and the battery.
You could plug them into one of the wireless shift levers, but they won't work unless you then connect the shift levers to the battery by wire.