User blog comment:Torquil/What should Luffy's gear 4 be like? ?(If you think he is going to get one...)/@comment-3075024-20121215192320/@comment-5387880-20121217193338

That will be with gear 3, he will just put air in all his body, but that would be only  useful in attack because in the defensive if he lose his air he will go like a baloon..