A sort of watchmaker tank! She has a reassuring thickness but hardly compatible with shirt sleeves! It passes under the shower, in the pool, in the garden soil, sawdust from the chainsaw, sand and so on! Cleaning with soap under the faucet and that's it. It advances a little (about 30s / day), but it probably will calm down with time. It's an automatic, not a quartz (1) Only one small complaint: the price (it can be found cheaper on the WEB) and day names in English or Spanish ...!
(1) As expected the mechanism was "set up" and now it varies more than a few seconds per day (less than 5), provided of course to wear regularly (power reserve approximately 36 hours), or the back hand.