SPEEDO Mens Boom Splice Jammers - Black/White (Various Sizes) New. Sizes - 26-28-30-32-34 inch waist DESCRIPTION Great for fitness training, and featuring a splice of Speedo's signature print Boom, these jammer hug the contours of your body to create a smooth, hydrodynamic shape in the water. Made from 100% chlorine-resistant Endurance®+ fabric, they offer total freedom of movement so you can focus on your swim.