Shimano drilled lightweight 10 speed cassette designed for super Narrow 10 Speed HG chains. Dyna-Sys is Shimano's next generation MTB 10-speed drivetrain system. The CS-HG81 10-speed cassette sprockets have a spider arm for 3 low sprockets.
. Dyna-Sys technology
. For super Narrow 10 Speed HG chains
. 10-speed drivetrain system
. For mountain bike
. Spider arm for 3 low sprockets
. Available in gearings 11-36T and 11-34T