A guards coat is a men's topcoat which has a half belt in the back, and is based on the coat of the Officers of the Guard. It can be buttoned with three buttons or just two. A guards coat is similar to a Paletot. The Guards coat has peaked lapels and welt pockets and comes mostly in formal colors such as a deep navy or midnight blue, and is more formal than the Ulster coat.
References
Guards coat Wikipedia(Text) CC BY-SA