Powerful Battery, 21 Soothing Sound, Noise Canceling for Office & Sleeping, Sound Therapy for Home, Travel. Max has more skills. Designed for all things sleep, this sound machine comes with favorable features: rechargeable battery, 21 soothing sounds, customized timers, various volume levels, child-lock for safety, and even memory functions! It is not only a sleep soother sound machine for baby kids, but also an effective white noise machine for adults sleeping & relaxation. 【HUGE BATTERY, WORRY-FREE ON THE GO】- Everything D11 max has, PLUS a LONG-LASTING battery. The portable sound machine is built with unbeatable1800mAh battery compared with 500mAh of others. Easily lasts through the night and into daytime naps on a single charge. For parents who are worried about baby getting naps on the go and especially when the power goes out, it is definitely a life saver! Battery is built in (comes with a USB-C cord to charge) so no need to worry about buying any.