Remote Satellite Sprint Shifter
The Shimano SW-R9150 remote satellite shifter can be positioned anywhere on the bike's handlebars. They're used for quicker shifting during climbing, when the rider's hands are on the bars.
These switches effectively replace the SW-R610 sprint shifters, that only work in dedicated sprint shifter ports as found on the ST-6870, ST-9070, ST-R8050 and ST-R9150. The SW-R9150 will work in normal E-Tube ports, meaning that you can also use them with hydraulic shift levers (ST-R8070 / ST-R9170 and GRX).
The wire length on these switches is 261mm (each).
These satellite shifters are 12-speed compatible, if you update them to firmware version 3.3.0 or newer.
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.