Spiral shields are more flexible than braided shields and are easier to terminate. They are highly recommended for audio applications and have a shielding effectiveness of 80-97 percent.  Foil shields are made of a laminated aluminum and polyester tape wrapped around the cable with an overlap. They have limited flexing and a shielding effectiveness of 60-70%. Foil shields are unique because they include a tinned copper drain wire that touches the metal side of the foil shield. This drain wire functions as an outlet for EMI to ground and makes the cable relatively easy to terminate, an otherwise relatively impossible task.