I purchased this used about six months ago, but haven't had much opportunity to use it, so I'm putting it up for sale. It's a 2x teleconverter. The mount is Canon EF. There's almost no dust or debris on the lens, and I don't see any clouding. However, possibly due to incompatibility with my camera, it sometimes struggles to focus smoothly when used with my camera. Due to the above, please understand that this is a junk item before purchasing. As it is junk, returns are not accepted. Thank you for your understanding.