If you are in need of a reliable and durable "This door must be kept closed" sign, then look no further than the IMPA 335801. This high-quality sign is designed to meet the safety standards set by the International Maritime Organization (IMO), ensuring it is suitable for use in marine environments. Made of durable materials, this sign is built to withstand the harsh conditions at sea, making it a dependable safety measure for any vessel. With clear and bold lettering, this sign effectively communicates the important message that the door must be kept closed, helping to prevent accidents and maintain a safe working environment. Trust the IMPA 335801 to provide the safety and security essential for maritime operations.