Strong and Comfortable Material : Outer strong memory foam and Inner silicone tube.There is a buckle inside to hold tightly with earbuds. Break Strength is over 22 lbs. Rebound time is over 60 seconds which is much better than 90% market normal foam. Fit in the Charge Case: Perfect with earbuds. There is plastic buckle which can hold the earbuds tightly. The earbuds also has the dust filter. Enhance Sound Quality : The memory foam tips noise isolation offers superior audio experience enhanced bass and good seal block out external noise. Packing List : 4pairs/pack with S.M.L.XL size . One pair for each size. Packed by hard PP box to protect very well. Ultra soft and soft memory foam eartips. 4 sizes with XS/S/M/L eartips in the packing.