Anthony F.wrote a review of Shimano Ultegra CS-HG800 Cassette on April 24, 2018
This item allows us to use that nice 10 speed wheelset sitting in the corner because you bought a new bike with 11 speed.
Shimano even thought of installation and tried to make it as easy as possible. The cassette comes packaged on a plastic alignment tool that slips on to your existing hub. Align the grooves and slide everything over to your hub all at once. Its literally that easy.
I personally run this cassette on a SRAM Force 22 drivetrain with a med cage derailleur and 50/34 chain rings.
It is super sweet and the 1:1 ratio made choosing a cadence while climbing so much better.