Very rare, very high quality MaSuKo stainless steel film developing tank. These are almost unknown outside of Japan and highly sought after. The system uses unique film reels which are incompatible with traditional stainless steel tanks, but which funnels the developer into the tank in a way that ensures more even development. The tank also takes more chemistry than traditional tanks (1200ml) which likewise helps with even, consistent development--there's definitely a difference I've noticed between this tank and other systems. It's also a beautifully made, finely crafted object.
The reels are designed for 220 film but work fine with 120, just practice a little with a spare roll until you get the hang of it. The small metal top cap fits a bit loose (the main large cap keeps the tank light tight), but it never bothered me and it was even helpful as it allowed me to change chemistry fast.