Features: 1. High quality material, durable clear plastic, metal contact on the top, which make it work well in many devices 2.They are not only used as AAA to AA battery converters, but also as protective case for your AAA batteries. Be dry and dry to store your batteries 3. Easy to put in and take out your AAA batteries, easy to carry, easy to use 4.The upper and lower parts of the battery case lock well. When you want to separate them, give them a slight twist and they separate easily. 5.Standard size battery holder converter fits all AAA batteries and all devices that use batteries AA Specification: Material: PP Color: transparent Size: 50*14mm Quantity : 4pcs Package includes: 4* battery cases AAAA TO AA adapters have metal contacts on the bottom part. If there is none, AAA TO AA battery adapters will not work in many devices Adapter Material: High quality and durable transparent plastic on the bottom AAA TO AA Battery Converter: Switch AAA battery size to AA or 14500 battery Easily keep your battery close at hand, at home, in the office, camping, etc Nothing complicated, just stick the AAA battery in the converter and it's the same as an AA battery