A Description of Mrklin (Marklin) Metal Track

A Description of Mrklin (Marklin) Metal Track
Marklin HO train tracks have two outer rails and a center rail. There have been three general types: M (metal), K (Kunststoff, German for Plastic), and the newest C (click) track.
Within the family of M track are 3 different types with a metal (M) roadbed: 1) 3-Rail (aka 3600-3700 series) with a metal base and a solid center rail, 2) Model Track (aka 3800-3900 series) with a metal base with a plastic insert road bed with studs in the center, and 3) the gemon M Track (aka 5100-5200 series) with a metal base with studs in the center. These tracks have been made in various radii as shown below.
Industrial Curve 286 mm Only available as M Track 5120
Standard Curve 360 mm 3Rail Track 3600A and M Track 5100
Big Curve 437 mm 3Rail Track 3700 and M Track 5200
Bigger Curve 536 mm Only available as Model Track 3800
Biggest Curve 586 mm Only available as Model Track 3900
These M tracks can be connected to each other without adaptor transition tracks.
The very cool thing about Model Track is that it has much LARGER curvatures than the other tracks. It was intended for more grandiose layouts where space was not limited. It also had plastic inserts between the metal roadbed and the train rails to reduce the running noise. It only sold for a few years (1953-56), did not sell well, and was discontinued. It is rare to find, and gemands a premium price.
History of Model Track (Modell Gleis):
Marklin purchased the license for their Modell Gleis from the French Firm Vollard