Fins
 
Fins help provide a large surface area so that your leg muscles can help propel you through the water. This is much more effective than swimming with your arms, although some divers with limited leg use use their arms equipped with special hand fins instead.
All fins, regardless of style or features have pockets for your feet and blades for propulsion.
Here are a few examples of fins:
 
V-Drive by Oceanic
V-Drive by Oceanic
Floating Snorkeling Fin by Oceanic
Floating Snorkeling Fin by Oceanic
for more information on regulators and pistons, please visit these sites :
Oceanic
Mares