A hands-on look at the new Garmin TT/Tri Mount, the Seat-post Quarter Turn Mount, and the D-Post insert for the Varia that ships with the newer Varia Radar units and is now available as an after-market purchase for those with older Radar units (RTL500/510/511).
Varia™ Universal Seat-post Quarter Turn Mount
Amazon US: https://amzn.to/32INAET
Garmin Direct: https://buy.garmin.com/en-US/US/p/521431
(Garmin inform me all the Universal mount kits now have the “D” included)