Harley XL Ironhead Sportster Compensator Nut, 1957-E76 (OEM #40386-57)
Early style nut. A bit weathered from long term crate storage. But threads are straight. Some flaring of the nut wrench holes, but still generally fair condition.
For reference, overall length measures 2 3/4". The Panhead version was a bit shorter.
121520 TS (OS)