Composite Decorations are a pre-made assemblage of decorations that will help you decorate your park more quickly. They come corner, straight, cross and plaza pieces that you can mix and match to surround your rides or decorate your paths.

Unlike normal decorations, Composite can be re-colored with 3 up to colors. To do so, select the Composite, tap on the color wheel and assign it color, just like you do with rides. Every color card you own can be used on a Composite.

Composites have better decoration stats and area of effect than if you placed each individual item alone. And they do not require you to own the individual pieces to be able to place it. They are stand alone objects. 

You will find them in most of the card packs, but completing certain achievements will give you a pack full of Composites.