Buck magnet and steel cup for E100, E100HD and Hd+. Easy to attach; just put the centering ring around the bottom of the E100 magnet and let the shield snap on to the magnet. Glue is not neccessary, but you can use epoxy for example, should you feel the need for it. The shield will not affect the sound and parameter changes are very small. The shield is normally only used whenever you place the speakers close to a CRT screen or any equipment sensitive to magnetic radiation.