6.75" Component Speaker Box Enclosure Kicker CSS674 Car Speakers Coaxi – AK Audio
Enrock Harley Davidson Speaker Mounting Ring Adapter for 6.5 Inch to 6.75 Inch (6-1/2" to 6-3/4") Speaker Fits 1998-2013 Harley Davidson Touring Models - Walmart.com
The Big Guide To Car Speaker Sizes (Plus Great Installation Tips!)