The Kydex Wasp is the newest addition to the Midtech wasp family! S/A Stands for Single Action, which means the blade is deployed at the push of a button and retracted manually. The biggest difference between a single action & double action OTF besides the manual reloading, is the blade play. Our Kydex Wasp features virtually no blade play! We also upgraded the internals slightly to help with the single action feature of this knife, and gave the blade a complete makeover. Don't let its size fool you, our mini wasp series boasts solid action and a size that is ideal for concealed pocket carry. The handles are made from milled aircraft aluminum while the blade is made from 440C Stainless Steel. The firing button is mounted on the front scale, and two key chain holes on the kydex sheath for every day carry.