When I started Zero Wetsuits in 1988, I searched for a company that made rubber lighter than Sed Science, and ended up with National Bond's National Rubber, which I still use. My belief is that surfing wetsuits should be light. However, at that time, diving wetsuit makers had great power, and even now, they have decided that light rubber is useless because it is worn out, so such rubber cannot be used. So, when I brought it to National Rubber, "Would you like to make a light rubber?", I was refused, "No, I can't use that kind of rubber." But I said, "I'll use it for myself, so that's fine." If you make it with that, as expected, when it is completed, it is much lighter than itself. Since then, I used to say "light wet, light wet", but now diving wet is also light. Lightness has become mainstream. However, the diving wetsuit maker's "sag" is water pressure. Divers dive 10 meters, 30 meters, and 100 meters, so if you dive 100 meters, the pressure of 10 atmospheres will be applied to the wet suit, so the rubber will become messy. 10mm thick rubber becomes 2-3mm thin. When rubber becomes pettanko, it's naturally cold. I will talk about a research report, but the heat retention is the thickness of the rubber. There is a report that the thicker the rubber, the better the heat retention. In other words, when 10mm thick rubber becomes 2-3mm thin, it's naturally cold. The diving wetsuit makers don't like it because it leads to poor quality. But we surfers don't dive into the ocean, at most about 2 meters deep even if they are caught in the waves. It's coming up soon, so it doesn't matter what the water pressure is. Rather, we're in the same environment as we're wearing on land, so to speak, we're surfing in the rain. You don't have to wear a heavy wetsuit. Especially, if you are caught in the waves, you want to go up to the sea as soon as possible, so it is decided that lighter is better. So I persuaded National Rubber to make light rubber. Then, before I knew it, everyone started making light wetsuits even for diving wetsuit makers. Now it's easier to move, softer and lighter rubber is better. Now everywhere is starting to use that kind of fabric. (to be continued)