Expandable capacity - Increase the capacity of DELTA Pro Ultra with an extra 6kWh. *If you&';ve purchased three or more battery packs, please contact our customer service team to claim your EcoFlow Fixing Metal Tab, which is necessary for securely stacking your battery packs. Highlights: -One-Month Backup: 6kWh for up to two-day backup, scalable to 90kWh for one-month coverage -Space-Saving: Stack up the system in a neat, mess-free way -One-Minute Setup: With a plug-and-play design Specifications: Dimensions: 26x;18x;8 in (including mat) *EcoFlow DELTA Pro Ultra Battery must work with the EcoFlow DELTA Pro Ultra Inverter