These are Toyota Rear Spring Upper Isolators (Original Equipment).
Original Equipment Toyota Upper Spring Insulators (SPRING SUB-ASSY,). Used to delete the Air Suspension bags and replace with traditional Coil Springs.
Not needed if you are putting on coil springs.
Genuine Toyota 48302-35040 Spring Seat Sub-Assembly
Amazon.com: Genuine Toyota 48302-35040 Spring Seat Sub-Assembly: Automotive