ScubaLab, the U.S. Navy and several universities have conducted tests demonstrating that oral inflation is not as efficient as power inflation, which is also safer and easier. So use your power inflator, and save your breath. We have known for years that using a comfortable and properly fitting BC is important to your enjoyment and performance as a diver. If a BC is comfortable and fits properly, it is likely to perform better in terms of attitude, stability, ascent control and surface floating position. With most manufacturers offering five to seven sizes, you should easily be able to find one that fits.
Problems arise when BCs are offered in fewer sizes.
In an effort to save costs, some manufacturers attempt to span two or more size categories with one size. We have found that these sizes rarely fit properly. We have also found that many of the smaller sizes are simply scaled-down versions of larger BCs. When choosing a BC, don't compromise on fit. Flaring can cut your rate of ascent in half.