In certain situations, you might want to extend the borders of a clone layer. For example, when you apply a blur or some other effect that stretches pixels beyond the layer's boundaries. On Clones in Comp with a Set Matte effect, you simply need to use the Expand Borders slider on the Clone in Comp Settings effect. On Clones in Comp with a Calculations effect, you can, when creating the clone, automatically precomp the source and expand the border by a certain percentage. That way, the layer will have empty pixels around its boundaries onto which a blur, for example, can stretch pixels. When using Precomp Source & Expand Border, all transform properties of the layer will be adjusted in such a way that the image itself will stay at exactly the same position, even when keyframes were applied.