The Dual Flange Ear tip is an evolution in Etymotic design. Traditionally, using a 3-flange device, Etymotic ear tips allowed for 3 potential points of contact in the ear canal that seals the ear better than the single dome silicone tips on many products. What they have done with the Dual Flange ear tip is created a tip that is softer, more comfortable, and seals just as well as their traditional 3-flange tip. This package contains 3 pairs of the Extra Large size ear tips that are meant to fit Etymotic earphones. The widest outside diameter of this Extra Large tip is 12mm. These tips will fit other brands as well that have an inside diameter of roughly 3mm.