In standard form, the Yaris GR’s throttle body is plumbed into the cooling system’s loop and coolant is circulated around the outside of it.
This direct replacement silicone hose has been specifically made by Pro Hoses to remove the throttle body from the cooling system, which is required if you are changing to a bigger throttle body.
The kit features one silicone hose, two bungs to and two jubilee clips to effectively create a bypass loop.