SpinFit is a patented eartip. The flexible core design allows the ear tip to be inserted deeper into the ear, enabling less obstruction along the sound field dispersion path. Supreme Comfort Premium soft silicone material along with the ergonomic design provides outstanding and lasting comfort. OPTIMAL SEAL Consistent optimal seal even for headphones with an awkward insertion angle, allowing increased noise isolation. SOUND QUALITY Enhancement on treble and bass ensures a superior listening experience to the foam and the stock ear tips. EASY INSTALLATION Simple installation makes SpinFit an easy upgrade for your earphone. A perfect replacement for your stock ear tips. CP100Z Main Features: Eartip core has a inner diameter of 4 mm. Specifically desgined for True Wireless Earphones – Compatible with most True Wireless Earphones on the market. Comparable to CP100 with a shorter core. Aims for a tighter fit. Perfect for exercising. Outstanding isolation. FOR: Sony / B&O / Jam / Sol Republic / Samsung / KZ Note: Please Note CP100Z (L) Size does not apply to TFZ X1 wireless Bluetooth earphone. The package is 2 pairs in one pack,so if you purchase 1 pair,we will cut from the middle.