Old new stock, boxed NewerTech external intelligent dual battery charger for the original pre-unibody, 15" MacBook Pro. Load two batteries and when first battery is done charging, the unit "intelligently" begins charging the second battery. Plus, not only does this product charge your batteries quickly and correctly, but the deep conditioning feature can both extend the life of your battery, as well as bring back additional life to a battery that's started to show its age.