brown noise machine

They are commonly powered via USB, mains (AC) power, or batteries. Some listings state “No Battery Used.” When batteries are required, entries show either a non‑standard lithium‑ion cell or a CR2032 lithium button cell (installed or required).

Models range from pocketable travel units to larger bedside devices. Reported dimensions span roughly 2.44–7.24 inches in length, 2.5–6.58 inches in height, and 2.43–4.6 inches in width; listed weights vary from about 0.9 ounces up to 1.1 pounds. Many products are explicitly labeled as portable.

Yes. Many units offer sleep timers and auto‑off options with common minute presets such as 30, 45, 60, and 90 minutes; some models also include an 8‑hour continuous setting.

Cases are most commonly made from plastic or ABS (Acrylonitrile Butadiene Styrene). A few listings also show fabric used on the device exterior.

Listings vary: some devices indicate “No Battery Used,” others specify a non‑universal lithium‑ion cell, and some use a CR2032 lithium button cell (either installed or required).