An adjustment layer is applied just like a Final Cut Pro X Title, because it was made from a Title. Although there's no text, it is a very powerful tool to have. This allows you to place on top of several clips at once and apply effects to them all at once. Use Transform, Color board, blur, or even Lights and Shadows- basically anything else you may want to do to several clips at once on the adjustment layer and the effects pass through to the clips below it. I use it so much that I'm giving this away for free. I hope you enjoy it! Here's a video that includes one way to use an Adjustment Layer.