This object allows to manage the sharing rules for Asset object.
To enable sharing on the Asset object, go to Setup > Assets > Asset Settings:
Choose wether the Asset owner will be the object creator of the owner of the parent account.
Now go to Setup > Security Controls > Sharing Settings, change the Asset OWG (Organization-Wide Default) from Controller by Parent to Private or Public Read Only.
Click the New button on the Asset Sharing Rules to create a new owner based rule:
If you select a Rule Type of type Based on criteria you can also set Asset's fields criteria to decide which groups can share the record:
N.B. To enable access to this record, you have to contact Salesforce customer support.