This is a single first stage of the legendary Aqualung "Calypso." It's a tough model with a simple piston structure that operates stably even in harsh environments. Condition: Approximately 100 dives. There are signs of use such as plating peeling and scratches, but it is in good working order. Maintenance: Overhauled in December 2022 (unused since overhaul). Operation: Confirmed normal air supply by connecting to a tank in February 2026. *As this is a critical piece of used equipment, a final inspection before use is strongly recommended.