The low profile WTX-D30 wing is built with the single tank diver in mind. It's sleek design, low profile, and durable outer make it the perfect choice. The low profile dump valve, is also one of the best on the market in terms of size. Single cylinder wings, often referred to as donuts, are oval shaped air cells or bladders that are not permanently attached to a harness. While single cylinder wings have their origins in the realm of technical diving, they are becoming very popular in the recreational community. Not only are these single cylinder wings streamlined, but due to their shape being a continuous loop, they are very stable underwater. There is no dramatic shift of air from left to right. Apeks single cylinder wings are a smart design that allows a cylinder to nest deep inside them. These wings mate up nicely to the rest of the Apeks WTX collection of high quality harnesses, plates and accessories.They can be configured in multiple ways to match the type of diving that you do. As with the rest of the WTX collection, these single cylinder wings are built from the finest quality materials.