Mido Ocean Star Decompression Timer 1961 Turquoise Limited Edition FULL SET #197. I love this watch and have worn a dozen or so times as a desk diver, and that said I'm thinning out my collection since this doesn't get the wrist time it deserves. Runs absolutely perfect. No scratches on dial or bezel. Case is in great condition. Asking $1350. Reference: M026.807.11.031.00 Function: Hours, minutes, seconds, unidirectional bezel, decompression scale Material: Stainless steel Dimensions: 40.5mm diameter; 13.4mm thickness Caseback: Stainless steel Dial: Silver-white matte dial with multi-colored decompression scale Lume: Yes, Super-LumiNova on hands and hour markers Caliber: Automatic Mido Caliber 80 (base ETA C07.621) Power Reserve: 80 hours Water Resistance: 200 meters Bracelet/Strap: Stainless steel mesh bracelet, brown calfskin leather strap, and turquoise synthetic fabric strap with multi-color stitching Lug Width: 21mm Manufactured: Switzerland NOTE: The Mido Ocean Star Decompression Timer 1961 Limited Edition is not intended to replace modern diving rules and instruments. THE BACKSTORY Vintage dive watches are one of the most collectible genres of watchmaking, and within the countless number of watches built for underwater use from the 1950s to the '70s, a few stand out more than the rest. The Mido Ocean Star Powerwind 1000 ref. 5907 is exactly one of those watches. The Ocean Star Powerwind 1000 was one of very few dive watches to ever feature a decompression scale on the dial. While its colorful look appeals to collectors of all types today, it was originally designed for completely utilitarian purposes for divers to utilize when under water. How? Well, divers can develop gas bubbles in their blood that can cause illness due to water pressure if a diver ascends to the surface too quickly. To clear the gases prior to leaving the water, a diver must perform decompression stops on their way to the surface. But – and this is key – the individual stopping time will depend on both the length and the depth of the dive. That's why each colored ring on the new Ocean Star Decompression Timer 1961 Limited Edition corresponds to a depth (yellow for 25 to 29 meters, green for 30 to 34 meters, pink for 35 to 39 meters, and blue for 40 to 44 meters). The 1960s models were designed to feature either feet or meter indications, but the contemporary edition includes both (meters on the left; feet on the right). All that is required to use the dive table is to set the minute hand of the watch at 12 o'clock once a dive begins and then identify the depth of the dive in meters, or feet, on the black 12 o'clock scale. Once the minute hand reaches the number marked in black on the corresponding ring, you'll know how many minutes of decompression time are required on the dive. For example, if your dive reaches 35 meters, or 110 feet, your decompression time will be indicated on the pink ring of the dial. Once the minute hand reaches 30 minutes (indicating you've been at 35 meters underwater for that length of time), you will need 25 minutes of decompression time prior to reaching the surface. If that dive extends an additional 10 minutes to a total of 40 minutes (while still at 35 meters underwater), you will require 40 minutes of decompression time. It's all displayed in a simple and intuitive manner thanks to the color-coded design.