This is a replacement Arrma 8S-BLX Servo Saver Screw, intended for use with 8S-BLX Kraton kits. 
 
Features:
Precision manufactured for a perfect fit
Manufactured from high quality steel
High strength for dependable performance
Includes:
(1) Servo Saver Screw
(1) Washer 3.6 x 8 x 0.5mm