Never used! Manta description: Most comfortable Bluetooth® sleep mask in existence. guaranteed. Manta Sleep Mask SOUND gives you complete control over the two senses that have the biggest impact on your sleep: sight and sound. Designed for side sleep comfort, the razor-thin Bluetooth® headphones are nestled within a ventilated strap — while the C-shaped eye cups ensure zero eye pressure and a perfect blackout seal without bulk. The result: unmatched comfort as you listen to the sounds that soothe you — so you get the best sleep you’re capable of. 100% BLACKOUT C-SHAPED EYE CUPS RAZOR-THIN HEADPHONES ZERO EYE PRESSURE