Compatible with all sizes of 18650, 18700, 20700, and 21700 batteries. DIY the power bank capacity by simply replacing the batteries. Dual-port output and fast charging. As a charger: 3hrs nearly fully charge 2 x 21700 5000mAh batteries. As a power bank: about 1.5hrs fully charge an iPhone 13/14. Easier to carry with removable locking spacer and rotating plastic piece.