Subaru 2005 Legacy Owner's Manual page 561

Maintenance and service
A) Metal spines
2. If the new blade rubber is not provided with two
metal spines, remove the metal spines from the old
blade rubber and install them in the new blade rubber.
11-62
3. Align the claws of the metal support with the
grooves in the rubber and slide the blade rubber as-
sembly into the metal support until it locks.