Throttle Servo Holder with Enhanced Airflow Capabilities.
This is a running change in kits, and the new spare part numbers have an added A at the end. This is only really really relevant for hot climates, over 30C degrees, where the additional airflow around the servo, as well as the carbon shims insulating from heat transferring into the throttle mount helps keep the throttle servo cooler.
We also recommend you drill holes in the plastic mount, and cut the outer vertical tab off, as you can see in the images below.
Choose the long version to reduce Chassis flex and ensure the same length with your engine mount for balanced flex!