Uniden(r) 3.6V 800mAh Ni-MH Cordless Phone Battery for BP-446
$24.95
At RadioShack on 9-4-2008.
This rechargeable Ni-MH battery fits Uniden T-400, 500 and 600 series cordless phones. With 3.6V of power and 800mAh of capacity, the conversation can keep going strong.