Boyesen Pro Series Reeds 62 Rad Valve Polaris ATV 350/400 The latest carbon fiber technology with all the advantages of Boyesens patented dual-stage reed design Utilizes a carbon fiber top reed and a durable fiberglass/epoxy bottom reed Offers the quickest acceleration any reed can offer; maximizes horsepower and torque Responds quickly and accurately to changes in piston speed for smooth, dependable throttle response No sacrifice in reed life like traditional carbon fiber reeds