The N-3 evolved into the N-3B by 1958, described as "for aircrew members in extremely cold environments." The N-3B was a single breasted, four pocket, 3/4 length parka with an outer layer of nylon twill (typically sage green), insulated with a layer of wool pile fabric and lined with nylon cloth.

The N-3B design is renowned for its hood, which is trimmed in very expensive, luxurious genuine coyote fur.