🔹Double Sound Machines & Immersive 3D Stereo Sound: The white noise machine can be used individually, or two machines can be used simultaneously. 2 pack sound machines play simultaneously to experience the stunning 3D surround sound and create a rich, high-definition audio environment. It is perfect for deep sleep, concentration or relaxation. Outperforms single sound machine with enhanced noise cancellation that masks TVs, traffic, and loud conversations. Experience unparalleled sound quality that delivers powerful, well-balanced sound with minimal distortion. 🔹Single Use & Compact Yet Mighty: One portable sound machine baby delivers surprisingly 32 adjustable volume levels loud and clear audio far superior to standard mini white noise machines. Lightweight with a braided lanyard for easy portability wherever you go. The travel sound machine is perfect for hang it on the stroller，handbag，backpack and pocket. Ideal as a travel white noise machine for baby, adults, hotels, flights, or quick naps. 🔹30 High Fidelity Soothing Sound: White noise machine baby with brown noise, white noise, pink noise, fan, rain, train, sea wave, bird, fire, lullabies, meditation and so on. The high fidelity soothing sound of the sleep machine to create a comfortable environment for baby, home, office and travel. 🔹Double Sound Machine up to 40-Hour Battery Life: You can get up to 20 hours from a single sound machine or extend to 40 hours by alternating between two sound machines. You can enjoy uninterrupted from day to night without any distractions. 🔹Memory Function and 4 Timer: The soother sleep sound machine can be played continuously or 30, 60, or 90 minutes auto-off timer, it is good for taking naps, relaxation, concentration while studying and working. Besides, the travel sound machine with memory function to remember the last sound and volume level, no need to reset next use,whether you use one or two machines. Immersive 3D Stereo Sound, the white noise machine has 30 kinds of non-looping sounds: 1. Brown Noise 2. Pink Noise 3.White Noise 4. Soft Fan 5.Loud Fan 6. Rain on Yard 7. Heavy Rain 8. Rain on Window 9.Thunder Rain 10.Stream in the Cave 11.Brook 12.River 13.Gentle Sea Wave 14.Mighty SeaWave 15. Little Sea Wave 16.Water Drop 17.Singing Birds 18.Campfire 19.Fireplace 20.Train 21.Brahms Lullabies 22.Lullabies 23.Subote Lullabies 24.Heart's Beating 25.Hushing Sound 26.Piano 27. Bless Song 28.Alpha Wave with Dripping 29. Stars in the Night 30.Meditation