From HB Racing:
These universal shafts are precision machined from high strength steel. They’re standard replacement parts for the D817 buggy, and a tuning option for other HB Racing vehicles like the E817, D815 and RGT8. Universals offer improved bumpy track performance and ease of maintenance compared to CVA joints. The 204016 front universals can be used on the front and rear of the D812 buggy. Sold in pairs. Compatible with: D817, E817, D815, RGT8. The front universals can be used on the D812 front and rear.