This fits well for my gf. Works on a narrow jaw

These things are awesome. Don't let other reviews complicate a simple awesome design. It takes 7.89 seconds to figure out how to use them and your set. Very cool experience in the bahamas with these

I swim an hour a day, 5 days a week, summer and winter. I have a vertigo condition that presents me from turning my head side to side. In the past 20 years I have used every breathing mask/snorkel devise I could find. Prior to that I was a SCUBA diver in Hawaii, using different mask and breathing devices. Most work adequately but resulted in jaw stiffness biting sown on the snorkel mouth piece for an hour. I bought the full-face mask in April, 2020, and have a couple of hundred hours of use and experience with it. The following comments are based on the following conditions of my use. I swim either in a pool or calm freshwater lake, no open, wavy water. I have short hair and no beard. Using the mask sizing guide, I measure 5.0 inches, which is greater than 4.7 on the chart, so ordered an L/XL.
PROs: 1. A single piece of equipment (plus the air tube). 2. Largest viewing area around. 3. Adequate air supply, for moderate exertion.
CONs: 1. The single biggest concern is the tab used to "lock" the air tube to the mask. Once the tube is seated, the tab has to be pried back to remove the tube. This creates flex stress on the tab that eventually will cause it break. In the mean-time the tab is flexed away from the tube each time you use it, making a secure lock difficult. 2. There is on O ring where the tube attaches to the mask. If the O ring is not fitted absolutely perfectly it is almost impossible to get the tab to close over the locking hole. 3. When the air tube dips below the water line, even slightly, water (small amount) enters the mask across the top of the face plate. 4. No matter how tight or loose you tighten the straps, or how far up or down on the forehead you fit the mask, small rivelets of water seep in, requiring clearing the mask every 5 to 10 minutes 5. Most annoying to me, as a face-straight-down swimmer, is the angle of the air tube. At the current angle, when you are facing straight down, the air tube encounters the water and breathing is blocked. Consequently I have to swim with my head and neck cocked back 5 to 10 degrees, making for a stiff neck.
I would rate this device an 11 if the air tube attachment tab/method was improved (an easy fix), the face seal thicker/softer, to allow for all the contours of the human face (a big ask), the air tube was angles back 5 to 10 degrees, and the (do-able ).
OPINION: 1. Keep the clear face shield protected from scratches. Dry it inside and out immediately after each use, to keep it clear. 2. Minimize the number of times you remove the air tube, to protect the tab. At this point since I do not travel more than 100 yds with it, I never remove it. 3. Even though this is advertised as a "dual flow" air system, one way in another way out, I keep my mouth closed and inhale and exhale through my nose.

I was teaching my daughter how to swim and it was taking longer than expected. I bought this because a friend recommended and within two days my daughter was able to swim without the mask. It helped her to not be afraid of going under water and practice holding her breath by protecting her face.

I have 5 and 7 year old grandsons. They swim with goggles, but have never had any sort of snorkel gear on before - they tried these on and immediately began to swim/breath without missing a beat. I think these would be great for beginning swimmers - so much easier to learn the strokes without having to incorporate breathing right away. The boys loved them.