10" x1"E-Rings™ Filler Pack The E-Ring is an easy-to use external overtone control ring which "floats" on the surface of a drum head. It removes overtones and flattens the drum head's sound and allows for easier tuning. Available in 10-Pack 'Fillers' for 10", 12", 13", 14", 16" and 18". E-Ring Pre-packs are available, matching the most common drum set configurations.