HAG is a Swiss maker of model trains. The company was founded by Hugo and Alwin Gahler on 1 April 1944 in St. Gallen, Switzerland.

The Gahler brothers originally manufactured model trains in O scale

O scale

O scale is a scale commonly used for toy trains and model railroading. Originally introduced by German toy manufacturer Märklin around 1900, by the 1930s three-rail alternating current O gauge was the most common model railroad scale in the United States and remained so until the early 1960s...

 but due to competition, particularly by Marklin

Märklin

Gebr. Märklin & Cie. GmbH or Märklin is a German toy company. The company was founded in 1859 and is based at Göppingen in Baden-Wurttemberg. Although it originally specialised in doll house accessories, today it is best known for model railways and technical toys...

 H0 scale, began the transition to H0 in 1954 with their final O scale set being manufactured in 1957.

Today HAG manufactures die-cast metal

Die-cast toy

The term die-cast toy here refers to any toy or collectible model produced by using the die casting method. The toys are made of metal, with plastic, rubber or glass details. Wholly plastic toys are made by a similar process of injection moulding, but the two are rarely confused...

 model trains and is the primary manufacturer of HO scale Swiss model trains. Models are available in both two-rail DC and Märklin

Märklin

Gebr. Märklin & Cie. GmbH or Märklin is a German toy company. The company was founded in 1859 and is based at Göppingen in Baden-Wurttemberg. Although it originally specialised in doll house accessories, today it is best known for model railways and technical toys...

-compatible three-rail AC.