Construction

• Masks are generally made of silicone because it's non-allergenic and resists deterioration
• Frames and buckles are generally made from a hard plastic to reduce weight, lessen costs compared to metal components and to lengthen the life of your mask
• You may also want to consider a double-flanged face seal, a second sealing surface that further keeps your mask air- and watertight. Most masks now come with this feature.

Size

• Look for sizing indicators on each mask
• Most manufacturers label their masks to let you know if a particular model is made for a small, medium or large face
• Special models are aimed at smaller faces, especially geared for women and youngsters
• Low-volume masks are another option in sizes and shapes. This design uses less space which moves the lens closer to your eyes.
  • This offers more peripheral vision, decreases distortion, and enhances light transmission. Less bulk means less drag.
  • As a rule of thumb, smaller is better when fitting a mask, but never at the expense of a good, comfortable fit

Lens

Lenses are made of tempered glass, not plastic, to prevent distortion and fogging, minimize scratching, and to allow vision correction.

• Single lens
  • A single lens may be best for you if you do not have vision problems, especially since you may find trying to peer out of two lenses a distraction
• Double lens
  • A double-lens mask may help with vision problems
  • The double lens gives you a wider field of view without making the mask bigger, improving downward vision
  • These also allow you to buy special lenses to attach to the front
• Vision impairments
  • Those with eye problems should buy a front lens that compensates for the vision problem
  • As a rule of thumb, these lenses should be 10% stronger if you're nearsighted and 10% weaker if you're farsighted
  • This compensates for the lens being farther from your eyes
  • If you wear contact lenses, then you don't really have to consider this
  • You can find bifocal lenses from manufacturers and makers of specialty lenses
  • Color correction lenses are also available, a real plus when you dive deeper to see reds, oranges, and yellows better. The downside is on or near the surface when things look pink.
• Anti-fogging
  • Anti-fogging masks do as they say but will still require cleaning and defogging over time as sunscreen, makeup, and other elements come in contact with the lens

 Mask Features

• Purge valves
  • Purge Valves allow you to get rid of, or purge, water that leaks into and accumulates in your mask
  • The valves are generally located in the bottom of the mask's nose pocket
  • It works by gently exhaling to clear the mask of water
  • Purge valves will help you keep your mask cleaner
  • This option allows venting any water that leaks in so it's also a good choice if you have trouble getting a tight seal
• Nose pocket
  • All masks have nose pockets to enable you to pinch your nostrils before diving and prepare your ears by equalizing the pressure
  • Divers prefer to be able to do this with one hand but some models may require a two-handed method
• Field of vision
  • Nearly all masks provide a good field of view
  • Some options are available that offer benefits, albeit at the expense of other factors
  • Side windows
    • Give you a much better horizontal field out of the water but this is partially offset underneath the surface by water's refractive effect
    • Side windows also add volume to the maks
    • Many divers find it difficult to focus through these windows
• Color
  • The mask color also plays a role in your decision
  • A clear or light-colored mask allows more light in and gives you more peripheral vision
  • If you're new to diving, a light color helps reduce anxiety and overcome any feelings of claustrophobia
  • Lighter color masks though may discolor, become cloudy or yellow
  • Black works best if you want to take underwater pictures, because it reduces light and blocks out side movements
• Strap adjustments
  • Improvements have minimized fumbling with straps and buckles, especially underwater
  • Generally, buckles that pivot at the mask frame make it easier to place your strap
  • Straps with 2 parallel straps at the back of your head increase comfort over single straps
  • Your strap adjustment also may be easier if you select one with numbers marked on the strap. This allows you to easily remember your preferred setting so you can quickly readjust the strap after someone else has used your mask.

 Ensuring a proper fit

This is absolutely the most essential element in selecting a mask. A watertight and comfortable fit is a must. First, refer to manufacturer's specifications on mask size and match the specs to your face size. Once you get your masks, try these tests:

• Dry fit test
  • With your regulator in your mouth, look up while putting the mask on, but without securing the strap
  • The mask should touch all parts of your face evenly, especially your temples and the smile lines between your nose and corners of your mouth
• Suction test
  • Now do the same thing while trying to inhale gently. You'll notice how tightly it seals.
• Nose test
  • Put your gloves on and the regulator in your mouth and pinch your nostrils
  • Check to make sure you can reach around the second stage and reach your nostrils
  • The mask shouldn't touch your nose