Admin -> Backup -> Jobs -> <click RS name>) includes a drop-down to choose the size of the blocks in the blockstore, which gives benefits in certain situations.

From MMSP-6631:

DOCS: On the admin page for a job (Admin -> Backup -> Jobs -> <click RS name>), there is now a dropdown to choose the size of the blocks in the blockstore. The values range from 64KB (the current hardcoded value) to 15MB. Increasing the size of the blocks will result in faster snapshots and restores, at the cost of the blockstore using more disk space. The catch is that anyone either getting a horrible de-dupe rate (because they have lots of updates/deletes) or anyone with a fantastic de-dupe rate (because they are insert only) will get the benefits from increasing the blockstore without increasing their disk space. Everyone in between could tune between the min and max value if they desire.