MOXOM MX-PB237 20000mAh Power Bank with Built-in Cable

The cable is built in and doubles as the wrist strap, so the pack clips to a bag and the lead cannot be left behind. A carabiner holds the whole thing shut.

Twenty thousand milliamp-hours is about four phone charges, and at that capacity it stays inside the hundred watt-hour limit for cabin baggage — the carton says so directly, which is a claim worth having in writing. Twenty in stock.