This is the Replacement 72 Spur Gear for the Traxxas Nitro Rustler and Nitro T-Maxx Trucks. FEATURES: Black plastic, slipper clutch style spur gear. INCLUDES: One 72 tooth spur gear REQUIRES: The other parts of that make up the slipper clutch are: #1994 - tension spring TRAC7994 #4625 - pressure plate TRAC9625 #4622 - pressure rings TRAC9622 #4685 - friction pegs TRAC9685 #4185 - top gear shaft to slipper adapter TRAC4185 SPECS: Tooth: 72 Pitch: 32 2/4/97 BOX DIMENSIONS: 3.00" W. X .50" H. X 3.13" L. BOX WEIGHT: .03 LBS.