Core and Tubing is a combination part used to 1) mount Lloyds Mushroom Inserts and 2) connect those earplugs to a Behind-The-Ear hearing aid. The Tubing attaches to any make or model of Behind-The-Ear hearing aid by means of slipping about 1/4 inch of the Tubing over the end of the curved Elbow, or Earhook, of the BTE aid. All Elbows have a flanged ridge that grabs hold of the Tubing to keep that short, Straight Tubing securely in place. The Core is a small plastic right angle piece. One arm of the Core attaches to the Tubing; the other arm is the mount for the Mushroom Inserts. All five sizes of Lloyds Mushroom Inserts are designed to mount onto the Core.