This is a mount adapter for attaching EF-mount lenses to Micro Four Thirds cameras. It's the latest focal reducer from VILTROX. It has a structure that tightens the lens mount, eliminating the operational problems caused by looseness in the lens mount, which were issues with older models and other companies' models. I just bought it, but I'm selling it because I'm moving away from Micro Four Thirds due to personal plans. It's been used a few times and is in excellent condition, almost like new. By combining it with the SIGMA 50-100mm F1.8 DC HSM, which is also listed, you can use it as the lens with the most bokeh on Micro Four Thirds. You can find various blogs about how to use it and its feel by searching online. If you're interested, please consider the lens as well. If you purchase them together, please let me know before you buy. I'll discount it by about the cost of one shipping fee. Recently, there have been malicious claims of intentionally damaging products and switching items, so I will treat this as no claims, no returns, and junk condition.