The IST Pi Frameless provides a wide field of view, including downward vision, which is useful for seeing chest-strap releases, for instance. The skirt is unobtrusive, but does usefully increase your peripheral vision, so it feels good to use.
This is also a nice mask for photographers’ models to wear under water. I couldn’t detect any colour tint or darkening of facial images – some masks impart a green hue or make the face inside the mask look darker than the skin outside.
As this is a mono-lens mask, IST doesn’t offer off-the-rack eyesight-correction lenses. If you want to have this one corrected you’ll need to have custom lenses bonded to the glass.

In Use
The soft silicone skirt with its double-seal proved very comfortable on long dives. It sealed extremely well, even over two weeks’ worth of moustache grown specifically for testing masks!
The strap tightens by simply pulling the end of the strap and slackens by pressing two easily located push-buttons on the buckle.
You squeeze the buttons vertically between finger and thumb, so you aren’t pushing the mask forward to slacken the strap, which can lift seals and cause leakage, and the buttons were easily operable with 3mm gloves.
As with many mask designs, once the strap is released it tends to automatically loosen to the “perfect” tension, meaning that it’s tight enough to seal, yet not so tight as to be uncomfortable to wear.
I found it to be the sort of mask I could clear hands-free, which is a benefit if you do have a leak and your hands are occupied operating reels or a camera, for instance.
Breathe out through your nose and roll your head back, and the Pi Frameless drains quickly and completely.
I found the nose pocket easy to use, too – either for pinching my nostrils closed or for blocking them from underneath. However, this type of mask design can be unsuitable if you have been gifted with a large nose.

SPECS:
TESTER: Steve Warren
PRICE: £39
LENS: Single
COLOURS: Black, clear or white silicone
CONTACT: sea-sea.com
DIVER GUIDE 8/10