Hollis M4 Frameless Low Volume Scuba Diving Mask

Hold the mask against your face without using the strap, look slightly down, and inhale gently through your nose; a well-fitting mask holds itself in place for a few seconds. Check that the skirt seals all the way around without digging into the nose bridge, and that there are no gaps at the temples or above the upper lip. A mustache can break the seal even on an otherwise well-fitting mask.

New masks carry a residue on the inside of the lens left over from manufacturing, and defog cannot stick to it, so the mask fogs until that film is removed. The standard pre-treatment is to scrub the inside of the lens with a mild abrasive cleaner or a dedicated mask prep and rinse thoroughly, repeating if it still fogs. Follow the mask manufacturer's instructions, particularly on coated or mirrored lenses.

Apply defog to a dry lens before the dive, spread it over the whole inner surface, then rinse briefly with water just before you put the mask on. Fogging happens when warm moist air meets a cooler lens, so a clean lens with a thin surfactant film is the fix. Keep sunscreen off your fingers before handling the inside of the lens, because that film fogs badly and is hard to remove.

Dive mask lenses should be tempered safety glass because it resists scratching and, if it ever does break, fractures into blunt granules rather than sharp shards next to your eyes. Untempered or plastic lenses scratch easily and can craze, which is why tempered glass is standard on scuba masks. Look for the tempered marking etched on the lens.

Yes, prescription options are widely available, usually as masks fitted with stock corrective lenses in set diopter steps, custom-ground lenses installed in compatible frames, or bonded lenses added to an existing lens. Not every mask frame accepts replacement lenses, so check compatibility before you buy the frame. An optician or a dive shop can help translate your glasses prescription into a mask lens choice.

Rinse it in fresh water after each dive day and let it dry away from direct sunlight, avoiding anything abrasive on the treated inner lens. Store it in a rigid mask box so the skirt is never compressed or creased, since a set crease in the skirt is a permanent leak. Keep silicone skirts away from petroleum products and prolonged UV, both of which yellow and harden them.

Not tight at all in the usual sense, because over-tightening is the most common cause of both leaks and headaches; a hard-pulled strap distorts the skirt and lifts the seal off your face. The strap should sit high on the back of your head and be just firm enough to keep the mask from shifting. If you need it cranked down to stop a leak, the mask does not fit your face.

Each Hollis M4 ships with the mask itself, a rugged mask box and an adjustable mask strap. The box protects the lens and keeps the silicone skirt from being compressed or creased in a gear bag, and the adjustable strap lets you fine-tune tension so the mask stays in place without over-tightening. Nothing else is required to dive the mask.

Frameless means the M4 has no separate rigid frame around the lens, giving a lower-profile mask with less bulk and low internal volume. The result is a lower-profile mask with less bulk around the edges, a low internal volume and a design that stows easily.

Yes. The M4 is specifically designed as a low-volume mask, meaning there is less internal air space between your face and the lens. Less trapped air means less air to displace when you clear water from the mask and a smaller air pocket to equalize on descent, plus a closer, more natural view of the water around you.

The M4 is built around a silicone skirt designed to fit a wide variety of face shapes. To check your fit, hold the mask to your face without the strap, look slightly down and inhale gently through your nose; it should stay in place on its own. Call DiveCatalog at 888-701-4017 with fit questions.