This time it is the RMT Union striking against London Overground - those commuter trains with orange painted trains and represented on the iconic Underground and train maps by an orange line.
The strike is not by train drivers or train crew but by station staff and other ancillary workers. I don't know the impact to train running but if the stations don't open the trains won't stop.
This is a pair of 48 hour strikes, starting on both Monday 19th February and Monday 4th March.