Amazon.com : JGbike ~180g Lightweight 11 Speed Single Piece Cassette for Road Gravel cyclecross Bike, for Shimano Dura Ace Ultegra or SRAM Red Force for Triathlon - The Best Value Cassette Available :
NOS Shimano DURA-ACE 7800 CS-7800 12-23 10-Speed Cassette NEW OLD STOCK! | eBay