This is the Traxxas 1844X Servo Saver w/Adapters.

This Traxxas® Servo Saver is a replacement servo saver intended for use on the Traxxas Bigfoot No.1 Original BL-2s™ HD 1/10 2WD Brushless Monster Truck. Alternatively, this servo saver will also work as a direct replacement for the Traxxas Stampede Brushed or Brushless 1/10 2WD Monster Trucks. Designed to protect your servo by absorbing heavy impacts that can cause internal gear damage, this servo saver is an ideal choice for those seeking a long-lasting reliability. Additionally, this set includes adapters and a mounting screw for ease of installation.

Includes:
(1) Servo Saver
(2) Adapters
(1) 3x14mm Screw