Ness-Tech Baby Moon Low Gravity Non-Vented Screw-In Gas Cap. This cap is designed to fit the left side of fatbob style tanks. Ness-Tech Product 07-153.
Source: Custom Chrome
This low profile, between 1/4" and 3/8"-tall, chrome-plated billet aluminum design stands out in style! Ratcheting mechanism provides proper torque and alignment. Vented gas caps have a right-hand thread, and non-vented caps have a left-hand thread. Sold each.