A generally small pair [1 PAIR] of membranous wings on the back of a Whiffling. These wings may also be PARTIALLY covered in feathers, but no more than 50%, and have a sort of "shedding" effect, something akin to a mixed type of "angel/devil" wing. The membrane-aspect of the wings should be very visible and be the main attention on the trait.
Please note that dragon-type Whifflings may have a pair of membranous wings, but their natural pair does have scaling on them. They can have a secondary back membrane wing pair with this trait (that doesn't necessarily need scales on them).