The new Fill-In extensions are the perfect solution for filling out thin hair, matching your money piece or highlighted hair, or just for a boost of volume to thicken the hair around your face. This set contains 4 tracks to easily apply wherever you need them. If you are looking to fill in the sparse and thinning hair around the front and sides of your hairline, the Fill-In clip-in extensions are for you! Cashmere Hair Fill In hair extensions are best suited for those with thin/medium hair types.