Pack of 4 (9/16" x 3.5") high quality, Instrument Clinic, Premium Composite Cork. Thicknesses: .8mm, 1.2mm, 1.6mm, 2.4mm. These strips are perfect for use as key silencing cork. Apply heat to the key, stick the cork on and trim with a sharp razor. Saves shop time and leaves a very clean and professional looking job. Do not apply heat to the cork, only to a key that has been removed from the instrument.