After parting from Aladdin in 1968, W&B continued to supply the Military with the Bialaddin 305. The model then became known as the Vapalux M1. I believe the 1 1/4" filler cap was however quite soon changed to a 1" version because they certainly seem to be more commonly found on M1 models. About 1979 the M1 was discontinued and the Military went on to use the M320. The lamp shown is the latest date I have seen on a military M1. They also come with one piece green hoods. Some M1s do carry the M1 inscription but the majority do not. They just have the Vapalux logo. This has lead to a lot of confusion as to identification. Terms like HPP 1 (High Pressure Lamp 1) and 21C are military stores references and are not models.