This Spektrum S665 Standard High Torque Steel Gear Servo, 25T is compatible with the Arrma 1/7 Big Rock 6S 4X4 BLX RC Monster Truck (ARA7612), the Losi 1/8 8IGHT-XE 4X4 Brushless Racing Buggy (LOS04018) and the Losi 1/8 8IGHT-XTE 4WD Brushless Racing Truggy (LOS04020).