Model HG31 which i.a. can be used with Shimano Acera and Altus + other 8-speed systems.
The cassette comes in black color.
To install the cassette, it needs to be placed over your rear hub and finally secured with a locking ring, which is tightened with a key (puller) which has 12 pins. The locking ring comes with this item!
Guide to changing the cassette