Recon's aluminum cassettes are the very lightest available. They feature a 2-piece design; the 9 largest cogs are machined from a single aluminum billet, and the smallest cog is manufactured from steel. Multiple surface coatings give a unique appearance while increasing cassette life. These cassettes are ideal for use in hill climbs or special events - they are not recommended for heavy use or high mileage. To prevent premature wear, the cassette and chain must be kept as clean as possible.