This is the Hop-Up Option Touring Car Spring Set (Short Type) from Tamiya.
This will work for the 1/10th scale cars from Tamiya.

FEATURES: Three tensions to the spring set either Soft, Medium, or Stiff
springs.
Steel construction

INCLUDES: Two red neon soft springs
Two yellow neon medium springs
Two blue neon stiff springs

SPECS: Length: 23mm (0.92")
Diameter: 16mm (0.62")