The Coping Foot is a dome shape base for the jig saw that allows you to bevel, turn and pitch the blade while changing any of those angles during the cut. Any way the blade is angled the saw is supported right at the kerf. Making a twisting cut such as you would find in a spiral handrail is a skill easy to learn with a coping foot. When the saw is held by the barrel with the blade up, very clean, accurate and complex cuts can be made such as you would encounter coping skirting.
The Festool Carvex has the most complete set of jigsaw bases available. With the addition of a coping foot the Carvex becomes the most versatile saw ever manufactured. There’s nothing that compares to it.