GCE Zen-O portable oxygen concentrator. New, unused. Provides oxygen in two modes: pulse flow (up to setting 6) and continuous flow (up to 2 LPM). Runs on rechargeable lithium-ion batteries, and can operate for up to 8 hours in pulse mode. Features lightweight design (approx. 4.66 kg) and is suitable for use on the go or for travel. Approved by the US Federal Aviation Administration (FAA) for in-flight use. Includes technology that senses breathing rate and automatically adjusts oxygen flow to meet patient needs.