This is the Clutch Bell with Washer and E-Clip for the Revo.
Five cooling holes on the face of bell (bellow the teeth)
One clutch bell
Two teflon washer
This clutch bell uses different bearings than the 15T or 16T bell, you will need 5X10mm ball bearings TRA4609.
Diameter at the base: 15/16" (24mm)
Height: 11/16" (17mm)