In a sign of the road-centric times, Campy quit making track cogs long, long ago. The cogs best suited for an otherwise all-Campy track drivetrain are those made by Surly. Surly cogs are designed to spin onto standard ISO-threaded (1.375" x 24tpi) hubs, so they work with almost any English, Italian, or Japanese track hub we know of. The thread base is 7.4mm wide for maximum thread engagement, while leaving you with sufficient room for a lockring to thread on.
Surly cogs are available from 13-22t. They're made from machined, heat-treated, and chrome-plated SCM415 CroMoly steel. They're tough as hell, and they last an eternity. Please note that we only stock and sell the 1/8" tooth thickness. These are not compatible with 3/32" chains.