A back-inflate or Semi wing allows for more freedom of movement and creates a natural push to remain horizontal underwater. This is because the weight of the air bladder is placed fully on the back.Like a jacket, its general shape is still like a vest with pockets around the waist but the front is more streamlined and of course, there is no air bladder in the front. Instead, there are two air bladder pockets on either side of the pressurized air tank, somewhat similar to a scuba wing type.
More advanced divers appreciate that their underwater form is more streamlined with a back-inflate device. These divers are also more capable of staying vertical at the surface using a back-inflate design despite the extra push from the air bladder weight to pitch forward.
