Sennheiser MX 55 Ergonomic Twist-To-Fit Earbuds (Discontinued by Manufacturer) Exclusive Twist-To-Fit design that prevents the earbuds from falling out Sennheiser Basswind&#8482; system for big bass despite its compact size Customizeable fit and style with interchangeable ear adapters and design covers Includes durable carrying pouch Compatible with all MP3, DVD, CD, players and iPod.