XRAY Active Diff sections are CNC-machined from extremely tough metal, and have now really precisely-machined "V" ramp grooves with 90ð angle for simple engagement/disengagement. The segment is hardened to ensure long life and durability. The segments are laser etched with "90°" for simple and instant recognition. Pair of 2. The 90° sections provide a good balance of performance between on- and off-power. On-power the diff becomes difficult after a short delay. Off-power the diff becomes free after a short delay. For use on medium traction tracks. Active Differential Segments can be purchased 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