Goal Zero Tank PRO 4000 Yeti Expansion Battery Pack 3994 Wh Solar Generator 3600-Watt Output Push-Button Start Home Backup

Build out your backup system with powerful expansion batteries. You can combine as many as 4 Tank PRO 4000 batteries per Yeti PRO. This creates a robust backup system that can run essentials in your home, cabin, van or RV for days on end. And because the system is modular, you can get the expansion batteries you need now and easily add on more in the future when your needs change.