From HB Racing:
These sway-bar sets are additional tuning options for D817V2 Buggy, D817T Truggy, RGT8 and RGT8-E cars from HB Racing. They give racers a finer range of stiffness to help tune the car to track conditions. The Front Sway-Bar Set has 2.3mm and 2.5mm bars, and the Rear Sway-Bar Set has 2.5mm and 2.7mm bars, each labeled with a tag that shows the stiffness.
#HB204444 – Front Sway-Bar Set V2 (2.3, 2.5mm)
#HB204445 – Rear Sway-Bar Set V2 (2.5, 2.7mm)
Original Sway-Bar Sets for reference: