Use these 4 rechargeable NiMH AAA batteries in anything you have that requires AAA batteries. Use them up, when they are dead, recharge them. Do this again and again - on average about 300-500 cycles. You will feel smart when you save all that money and the landfill. These little babies have a Low Self Discharge which means they can sit on your shelf for 12 months before they start to lose effectiveness.