This set features a blue anodized aluminum mount, plus plastic bushings that just take the suspension shafts. Using various bushings and combinations permits fine-tuning of toe, tread, roll center and skid angle settings.
Follow this link to start to see the instructions, which includes explanations of how to use adjustable suspension system mounts in combination for different setups.
Appropriate Chassis TA07 PRO, TB Evo.7 TB-05 PRO, TRF419, TRF419X & TRF419XR Chassis
*The official Tamiya R/C Parts Matching List has an abundance of information about chassis suitable for Tamiya Spare and Hop-Up choice parts.