A watch’s water resistance in many cases is entirely notional. It’s pretty rare to see a cheap watch marked “ISO 2281”. The manufacturer estimates a pressure that it estimates there is an acceptably low probability of failure and calls it a day. Even under ISO 2281 testing is only a lot sample procedure. This is why the recommended use scenarios are absurdly conservative, it’s not that going for a swim can generate more than 3 bars of dynamic pressure, it’s that the 3 bar rating is a guideline not a guarantee. Where nightlights are concerned, Casio really got it right with this one. It has that just-right luminance that makes it a joy to use. The aqua color and contrast of the nightlight is also perfect. You couldn't ask for better. The first step was to simply immerse the watch under 5.5″ of cold tap water while pressing the buttons and observing for any signs of water ingress. Already, the watch proved it is far more than just rain resistant, so [Rotislav] decided to disassemble the watch and learn how it achieved this. Although I've not tested this, the F105W is supposedly 27g in weight while the F-91W is 20g. I don't feel the 7g difference if there is one, and I don't think anyone else would. In Walmart for example, you'll easily find the F-91W there as well as the F108 and the recently introduced W217 (very similar styling to the F-91W but larger with notably better nightlight.) But both of those models have an amber nightlight that while it does work very well, it's not the cool blue one.

The daily alarm reminds you of events that recur every day, by emitting an audible signal at the set time. The time display can be set to 12- or 24-hour format. In 12-hour mode, there is a p in the display for the second half of the day, i.e. 12 noon to 11:59 p.m. You get a 3 year warranty-certificate for your new timepiece. If there is any problem with the mechanism, this certificate garanties a 100 % protection- meaning we take care of the technical integrity inbetween these 3 years.People all over the world love the F-91W because it just works. The only complaint anyone ever has about the F-91W is that the nightlight is terrible. Solution? Buy an F105W. Problem solved. Synthetic resin is the ideal material for wrist straps thanks to its extremely durable and flexible properties. The daily alarm reminds you of events that recur every day, by emitting an audible signal at the set time. In addition, an adjustable alarm alerts you when every full hour has elapsed.

I don't know exactly when this watch was introduced to market, but it definitely came shortly after Timex released watches with the the Indiglo nightlight technology in 1992. My guess is that at earliest, the F105W is probably a design from the mid-1990s. Is the F105W exactly the same as the F-91W? On my 6.75" wrist, the F105W lays more flat than the F-91W, which is something I very much appreciate so the watch stays put. Does a nightlight really matter that much?Because of this, it isn’t uncommon to see individual watches exceed their rated pressures, and also to fail well below their rated pressures, even in the same make and model for cheaper watches.. Water resistance is an important feature of a modern watch. It makes wearing the watch far more practical in this modern world of sudden rainstorms and urban water balloon ambushes. The Casio F91W, one of the company’s most popular watches, is claimed to be water resistant to “30 meters”, which in ISO parlance, means it is suitable for splashes and rain resistance only. [Rostislav Persion] wanted to get a better idea of what this really meant, so set about investigating for himself. The daily alarm, in which an acoustic signal sounds at the set time, reminds you of daily recurring events.

While I described the W93H as a bit of a dud for me in my last article, the F105W is a total winner in my book. One model that Walmart carries that does have it is the A168. If you like a small digital with a steel bracelet, that's your watch. But if it's not, the resin version is the F105W... Elapsed time, split time and end time are measured with an accuracy of hundredths of a second. The measuring capacity of the watch lasts up to one hour.

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Natural resin is the ideal material for wrist straps thanks to its extremely durable and flexible properties. Elapsed time, split time and final time are measured with 1/100-sec accuracy. The watch can measure times of up to 1 hour. For those not in the know, the F105W is like the F-91W, but with one rather important improvement. The nightlight is a million times better. This is why ILLUMINATOR is so prominent on the watch face. Resin is made of synthetic resin and is the ideal material for bracelets due to its extreme durability and flexibility.

Given [Rotislav’s] results, we’d be far more confident getting our affordable Casio watches a little wet. Obviously, we wouldn’t expect to make a warranty claim if damage occurred from use outside the specs, but it’s clear the watch is far more capable than standards might suggest. If that’s not enough though, you can always set about modifying the watch to improve its water resistance even further.Technical amendments and errors excepted. The sizes in figures do not correspond to the original sizes. The resin housing is the ideal everyday companion. It is durable, lightweight and relatively insensitive to cold, heat or other external influences. and neither Walmart nor Target carry it as far as I know. Personally, I had to buy mine online just to get one.