The Comfort Tip is part of the iHEARHD, which provides secure and comfortable fit in your ear, and prevents feedback (whistling). You will need to select the correct size for your ear. The Comfort Tip lasts about 30 days, and costs about $3.00 per pack which contains 2 tips. A 1-month supply of Comfort Tips in all sizes is included with your iHEARHD purchase. Before you order more tips, try on the various tip sizes to determine which size fits you best.