HPW1002 Features: * Rechargeable batteries * 2 Rechargeable RCR123 batteries for the wireless collar * Can be recharged up to 500 times * Environmentally friendly * Ensure you have fresh batteries when needed * Recommended to charge your batteries nightly using the battery charger you received with the system * Batteries should typically last up to 3 days depending on the use of the system and activity of the dog Specifications: * 3.0 V, 650m Ah rechargeable li-ion battery Dimensions: * Dimensions: 1" H x 5" W x 7.3" D