A Dacron graft is a synthetic (man-made) material used to replace normal body tissues. It's usually made into a tube shape for use in replacing or repairing blood vessels. It can be a flat piece of material, too.

Sometimes the injured blood vessel can be closed just with stitches. When it can't and a graft material is needed to cover the hold, the Dacron graft works well. The body seems to be able to handle its presence easily.