This is the 2.5mm Mono Male to BNC Female Adapter. It features a 2.5mm Mono Male connector on one side. And a BNC Female connector on the other side. 3.5mm, also known as 1/8 inch, is an audio connector typically found computers, laptops, smartphones, and tablets. Not to be confused with 2.5mm, which is a little smaller and far less common than 3.5mm connectors. Or 1/4" connectors, which are slightly larger and are typically found on high end headphones and music equipment. The adapter will allow you to change your connection from BNC into 2.5mm The 2.5mm Mono Male to BNC Female Adapter is a quick and easy solution for your audio projects. For more information on our products, you can give our customer service department a call at 888-519-9505. For all your cable and connector needs, choose Show Me Cables.