Bests & Worsts Reviews from Amazon

I'm not a regular user of a sleep mask and purchased this primarily for the purpose of using on a long international flight. Upon receipt I was happy to find that it was just as described ~incredibly soft, lightweight, had no odor, and due to its XL size it completely blocked out any light. This mask has an elastic adjustable band that comfortably fits around the back of the head to hold the mask in place. I have tested it out a few times ~twice when I wanted to sleep in late but the sun was peeking in through the windows and another time when my husband was in bed reading with the light on...thankfully the mask worked great on all occasions. I had been eyeballing the various masks that are slightly domed shape to better accommodate REM sleeping (ie. rapid eye movement) however, there had been sufficient complaints (from other Amazon reviewers) and price discrepancies between the various masks that I opted for this since I did not plan to use it on a regular basis and did not want to spend a lot. I feel like the mask was light enough that it does not impede REM but I cannot say for sure since I don't have a way to monitor this. Confident it will meet my needs on the long flight especially when paired with a set of earplugs. Additionally, I was satisfied enough with the product that I bought a second one for my husband. Update 1/14/2015: Initially intended to only use on the flight but it came in very handy at the beach condo where the wooden shades in our room did not sufficiently block light. I still find myself using these on days I want to sleep in or during a midday nap. Both masks still look like new. Small side note, while not 100% guaranteed, a sleep app that I installed a few week ago indicates my REM sleep has not been effected negatively by using this mask. * how the app works ~you move differently in bed during the different sleep phases(awake, light sleep, deep/REM sleep), the app uses the accelerometer in your iPhone to monitor your movement and determine which sleep phase you are in. Very happy buyer, would buy this sleep mask again or recommend to a friend.