This is my third diver watch from this microbrandbrand. Ratio is relatively new, started in 2017 in Singapore. I am very iimpressed for the high build quality and specifications for an extremely reasonable price. It has a brushed stainless steel case with a matching H-band bracelet and a flat sapphire crystal. The helium release and crown are screw down and the bezel is a uni-directional 120 clicks with a (I think) ceramic insert. The lume is pretty bright and relatively long lasting. It has a Seiko NH36 day-date automatic, hacking movement with 21,600 BPH. All this for under $200! Expect to pay 2 to even 3 times that for a major brand name for these specifications.
Measurements are 46mm case diameter (50mm with crown), 50mm lug to lug tip, 15.25mm thick, 24mm bracelet that tapers to 20mm at the tri-fold double button release, which has 3 micro holes for sizing and 5 removable whole links with screw pins. This is a pretty heavy diver at 287 grams with all links installed, which I needed for my above average 8" wrist. I would say anyone with a 7.25" or smaller wrist may find this is too large, unless they like the look over oversized watches. And this may not work for anyone with a larger wrist as it just fit me, adjusting to the second micro hole without removing any of the links.
Design wise, it has a sword hour and arrow minute and second hands, large enough to clearly and legibly tell the time. Even with my old man eyes, i can read the day and date in its edged and bezeled window. The day is in both English and Spanish. The case back is screw on with the diver etched on. The yellow dial has a reflective metallic sheen and borders on gold. The lume is green and on the hour markers, all the hands, and at the 12 o'clock on the bezel. The movement crown has the Ratio Pi signature symbol etched on it, which is also on the clasp. As an engineer, I dig the Pi symbol.
As for its performance, it has a beat error of 0.6ms no matter the direction of the watch, but it gains 9 seconds a day while face down or on its sides and 16 seconds while face up. This is well within spec for the Seiko NH36, which is -20 to +40 seconds a day. It has a power reserve of 46 hours (tested twice). The lume is very bright after a few seconds under the UV light and is still quite legible after 5 minutes. I would have liked more lume on the bezel, such as on the numbers (10, 20, 30, 40, and 50). The bezel doesn't have any slop, loose tolerances, or back play, clicks quite audibly and positively, and is easy to grasp and rotate without being so easy that it'll move from incidental contact. The crowns screw off/on easily with the knurled edging and the movement crown clicks into first and second positions for adjusting day/date and time solidly and clearly. You'll definitely feel the presence of this watch as most of the overall weight is in the case itself. You could lighten the load by swapping out a nylon, rubber, or silicone strap. For me, it wears well and comfortably. The included bracelet fully articulates and can lie flat, doesn't jiggle or rattle, and it doesn't feel sharp or grab arm hairs.
In summation, I really like Ratio watches for the high build quality and specifications for a bargain price. The only negatives are that the bezel doesn't have illuminated numerals and I don't think there's any AR coating on the sapphire crystal. And the dimensions and weight of the watch may limit its viability to those between 7.25 (personal taste) to 8 inch (physically cannot fit after 8) wrists. BTW, the box it came in looks and feels nice and appealing enough to make it a giftable package, but it's not super strong or durable to continue using for storage or protection. But I'd rather they put more of the manufacturing costs in the watch itself over the box anyway.
I definitely recommend this watch for those who could wear it.