High efficiency battery Battery capacity is available 4000mah, use the best level polymer lithium ion battery, grade A, passed all necessary certificates, like CE, Rohs, UL, FCC, and so on. It is real capacity data, over 80% efficiency, as a sample, full 8000mah battery can charge an iPhone 5 for 4 times, a Samsung Galaxy S6 for 2.5 times. All materials and functions can be customized. Includes logo, color, power bank, USB flash drive, pen, calculator, card insert, paper, loose leaf binder, phone case and ipad mini holder. Paper refillable Stainless steel loose-leaf 6 ring binder, filled with 60 to 100 sheets of lined papers,5.5x8.2 inches, inch ring capacity can hold maximum 100 sheets. High quality. High quality and good feeling PU or real leather materials, professional handmade surface finishing, creative gift box packaging. Safety and reliable Interior 6 protection protects the batteries from damage due to getting knocked, dropped or crushed.