Traxxas 7047R 48 Pitch Spur Gear, 55T 48P, 55T spur gear.
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Traxxas 7047R 48 Pitch Spur Gear, 55T Part# 0-TRA7047R
Outer Diameter: 30mm (1.2") Inner Diameter: 5.5mm (0.22") Width: 7.2mm (0.28")