CRESSIOptical Lens -3.5 Diapter for Focus Mask

These lenses fit the Cressi Focus mask just fine, and it's a good mask.I'm deducting TWO stars because of the incredible frustration trying to figure out how to install the lenses in the mask. A single sheet of paper with a couple of illustrations would be so easy to include, but there is nothing!Once you understand HOW to remove and replace the lenses, it's pretty easy. But it is NOT intuitive, and I couldn't find anything online that explained it clearly.FYI, here are the basic steps:1. There is a small triangular piece of plastic at the top of the nose. This must be pulled straight out, as you look at the mask. You can see behind it that there is a little tab. If you push the tab towards yourself with a small screwdriver, that will push this piece out.2. There is a bridge (where a "uinibrow" would be) with the Cressi logo on it just above the piece that you just removed. That piece needs to be pushed straight up, towards the ceiling as you face the mask. It's just a friction fit.3. Here is the hardest part to figure out: the two plastic rings that hold the lenses in place. You can't just force them out. If you look carefully at the front of the mask around the outside of the two retaining rings, you'll see three areas about 1/2" long each, which is where there are little plastic tabs that stick out from the retaining ring and hold it in place. The ring is somewhat flexible, so all you need to do is get a fingernail (or something) on the outside of the ring near one of the tabs, and push inwards towards the center of that lens. This will get the tab out of its slot and allow you to pull it forwards slightly away from the lens. Do this for all three tabs.4. The old lens pops out at this point and you simply set the new lens in its place.5. The only tricky part about putting it all back together, is that you really need to exert some force when pressing the retaining rings back into position against the face of the lenses. The tabs need to snab back into their retaining indentations. If you put the mask face-down on a table, you can press down on the inside of the mask and that will help force the retaining rings all the way back into position.6. Now it's easy: simply replace the "unibrow" piece by pressing it straight down from above - you can see the plastic part of the mask that it slides down onto.7. Finally snap the little triangular piece back into position by pressing it straight in. Again, after it's out, it's easy to see how it goes back in.Sheesh, why couldn't Cressi have included this little explanation along with a few line drawings with their mask and/or lenses?

I was blind underwater, things looked fuzzy and out of focus. Now with Cressi Mask and Lenses - all is Clear. Each package contains 1 Lens only for right or left eye. Note that the Lens are Symmetrical (Almost a Water Drop Shape) and can be rotated to fit either Right or Left eyes. Takes about 10 to 15 minutes to replace both lenses if this is the first time you do this. following the instructions I saw in one of the reviews, I manged to change the first Mask in about 15 minutes, the 2nd mask in less than 5 minutes.I have captured the process and put some comments on each image. Hope that helps !

Only minor issue was with packaging. First package was empty. The internal bubble wrap envelope for the lens was not sealed and whomever packaged into the Amazon mailer sent an empty envelope. Replacement lens received without issues (Thanks Amazon Janet!)This is for nearsighted (negative diopter) scuba divers who don't want to spend a lot more money on a perfect prescription in a custom lens installation. The lens goes with the Cressi Focus Mask (separate purchase). I was told about this system by my optometrist, who said to get the closest diopter for my prescription and I would be fine (since everything is already magnified underwater).You do not need to specify left or right lens, they are interchangeable.

Picture shows 2 lenses. Description uses the word "Lenses". You will only get 1 lens. The lenses fit either L or R side. You will need to order 2 of these. If this was specified anywhere on the listing it would have saved me a lot of time.

these are good optical quality lenses. The same lens is shaped so it fit LEFT or right side on mask. If you have the same Rx on both eyes order "Quantity - 2"For different Eye Rx order one for each side with the associated DiopterIt is somewhat difficult to break apart the mask for mountingIt is worth the effort and the image is crystal clear

My prescription is -3.25 and it's recommended that for lenses that are only available in 0.5 increments, I should select the lower value, -3 instead of -3.5, for a dive mask. The advice is good! (-3.5 would have been a strong prescription, which would have worked too, but with my eyes getting older, I would probably have a harder time focusing on closer up objects, like gauges, so going weaker is better.)

This is a great lens to pop into the Cressi mask designed for prescription lenses. With such a large percentage of the population requiring glasses and/or contacts I am surprised that more companies don't offer prescription options. I have been snorkeling before and was frustrated in not being able to see much. Now everything is clear and enhances the experiences so much more. I highly recommend Cressi and the prescription lenses that are interchangeable.

I ordered this to self - install into a Cressi brand mask. the installation was trivial, and buying online saved me a bunch of money over buying it from a local dive shop. It was fairly trivial to install, and there are videos on youtube to help. you should also know that this lens matches more masks than just a Cressi branded one -- several brands use the same mask template, and thus identical lenses. I have a Cressi Focus brand mask, but from what I've read, the following masks also use the same lens:ScubaPro Fino Mask, Tilos Boom Purge Mask, Tilos Fantasia Mask , Dive Rite ES125 Double Lens MaskAeris Europa 2, Europa 2 Purge, Puropa 4 Maskstusa splendive 4,Dive Rite ES125 Double Lens MaskBody Glove Reliance Mask, Deep See Adventurer II Mask, IST IS-MK24Promate Sea Viewer Mask, Promate Pro Viewer MaskYMMV on the matching of course; I havent tried it . This was my first tome snorkeling, and I have zero experience changing lenses or anything else with diving masks, and I had no problem. A very small eyeglass sized screwdriver was helpful, as was a bit of patience.