The EcoFlow Extra Battery Cable (XT150 to XT150, 1 meter) can be used to connect your EcoFlow Wave 2 up to a compatible EcoFlow Portable Power Station, like the DELTA Max, DELTA 2, DELTA Max Extra Battery. 

It can also be used to connect the Wave 2 up to a DELTA Pro or DELTA Pro Extra Battery in combination with the Smart Generator Adapter.