The new 2008 Suunto Comfort Belts come with a textile chest strap making it the most comfortable training companion yet.100% interference free digital transmission technology is utilized in Suunto ANT belts and is compatible with the Suunto training instruments. . . . . Made from Textile Materials . . Stays snug with unique traction strips . . Pratical central closing mechanism and seamless length adjustment . . User replaceable battery . . One-Size . . Compatible with T3, T4, T6, T3c, T4c and T6c . .