Five "Mitsubishi 204 Acetylene Lamps" (carbide lamps) manufactured by Isomura Sangyo Co., Ltd. While there are no missing parts, there is some discoloration due to age. These are retro lighting fixtures manufactured for mining and civil engineering work. The following is an AI explanation: Detailed Information Purpose: Designed for use in mines and civil engineering. Manufacturer: Manufactured by Isomura Sangyo Co., Ltd. Mechanism: Acetylene gas is generated by a chemical reaction between carbide (calcium carbide) and water, which is then burned to produce light. Features: Compared to battery-powered lamps of the time, they could emit bright light for a long time, and many were made of durable brass. They were manufactured from the early Showa era to around the 1960s, and are still traded among collectors as retro antiques. No claims, no returns.