Better traction for off-road driving;Compatible with any XMODS Evolution Truck Starter Kit (not for older XMODS cars or Evolution cars);What's in the box: DEFF gear unit (1), Center gears (2), 2nd gear (1), Center shafts (M/L/LL) (3), 2nd shaft (1), 10mm bearings (2), 6mm bearings (4),Screws (4);You'll also need: XMODS truck starter kit

• XMODS Evolution Truck 4-Wheel Drive Upgrade

XMODS Evolution Truck 4-Wheel Drive UpgradeRadio Shack