XRAY Active Diff portions are CNC-machined from really tough steel, while having very precisely-machined "V" ramp grooves with 90ð angle for simple engagement/disengagement. The portion is hardened to make sure long life and durability. The segments are laser engraved with "90°" for simple and instant recognition. Pair of 2. The 90° segments provide a very good stability of performance between on- and off-power. On-power the diff becomes hard after a quick wait. Off-power the diff becomes free after a quick delay. For use on medium traction songs. Active Differential Segments are available in three different alternatives: #352123 - 60° #352125 - 90° #352127 - 120° Active Differential sections fit: #325100 - Active Differential for XB2/XT2/SCX #365100 - Active Differential for XB4/XT4 Font/Rear #365101 - Active Differential for XB4/XT4 Center