These high power batteries are direct replacements for 1.5 Volt batteries. They are suitable for any electrical item that requires batteries, especially when power and reliability are essential e.g. CD/MP3 players. Ni-MH batteries are good for up to 1000 charges and are better than Ni-CDs because they have a greater capacity and do not suffer from the "memory effect" that reduces Ni-CD performance. They are also recyclable, cadmium free, and environmentally friendly. Charge time is about 8 hours. What you get: 4 x AA Size Ni-MH Rechargeable Batteries .