Black Silicone Case & Screen Protector for New Apple iPod Touch 3rd Generation 3G - 8GB 32GB 64GB Higher energy density and lower weight than other types rechargeable batteries Battery tested based on International Electrotechnical Commission (IEC) standard to ensure capacity, quality and life time Lighting or other device needing 3.7V power Building portable power device needing high energy density and low weight Length 35.5mm x Diameter 18.5mm (+/- 0.5mm)