A freewheel is not a freewheel is not a freewheel. White Industries ENO freewheel is not some stamped and plated thing, but a CNC'd work of art. Chromoly steel teeth with a sealed cartridge bearing on the inside, seals outside, with 36 engagement points via a three-pawl mechanism, this is one sweet, high-tech freewheel. Threaded 1.37"x 24tpi, and works with either 1/8" or the derailleur-friendly 3/32" chain. We carry, 16, 17, and 18t cogs. 171g.