Chrome Non-Vented 2" diameter Fits left side gas tanks on H-D 1965-1972 Big Twins. Replaces Harley # 61103-65 These bayonet style gas caps (also known as cam gas caps) are non-vented and are chromed steel. This non-vented cap works with the left side gas tanks on H-D Big Twins 1965-1972. For more information read the differences for various year range motorcycles below. This gas cap replaces Harley-Davidson OEM # 61103-65. Here is a breakdown of the year ranges of Harley-Davidson motorcycles that accept bayonet style caps, the differences in the gas tanks / gas caps, and the Harley OEM numbers for each. This should help determine which gas cap(s) you need for your motorcycle. 1936-1964 Bayonet style gas cap both left and right, and both gas caps are vented. Both caps are same 'depth' in that they engage the cam bung on the gas tank in an identical fashion. Caps are approximately 2" diameter. OEM part number 61103-36 1965-1972 Bikes in this year range that take a single gas cap use OEM 61103-36. Bayonet style gas cap both left and right. The left side cap is non-vented and the underside is 'taller' than the right side, vented cap. This is because the cam bungs on the gas tanks are different left to right side, and gas caps are not interchangeable. Caps are approximately 2" diameter. OEM #s 61103-65 for the left, unvented and 61103-36 for the vented right (Same as earlier year range) 1973-1982 Bikes in this year range that take a single gas cap use OEM 61102-73a. Bayonet style gas cap both left and right. The left side cap is non-vented and the underside is 'taller' than the right side, vented cap. Caps are a larger, approximately 2.5" diameter and have a domed top. OEM #s 61103-073a for the left, non-vented and 61102-73a for the vented right side cap.