These batteries in 4 to 8 hours with 4000 mW power. It can charge 2 or 4 batteries from any brand simultaneously, featuring auto shut-off and an LED indicator. It includes rechargeable batteries that can be recharged up to 400 times and last for 10 years. The price drops from $33.59 to just $14.99. Shipping is free for Prime members. Else, it adds $6.