Create a calming environment with soothing sounds designed to help promote sleep. This white noise sound machine is compact size which makes it perfect for traveling or gifting. Micro SD card includes 20 calming sounds, including nature sounds and pink noise, curated based on Alpha, Beta and Delta brain waves to help coax you into a state of restfulness. High fidelity sound quality. Can also be used as a Bluetooth speaker with a 30-foot range. Built-in rechargeable lithium battery allows for 4-5 hours of cordless use on a single charge. Find the instruction manual in for everything you need to know about the Sleep Sound Therapy System.