The ZhiSu 4x4 M Mini is part of YJ's mini magnetic series. This puzzle is 56 mm, which is about the same size as a regular 3x3. This cube weighs 95g and comes with spare magnets, a cube stand and a screwdriver.
Also available in this series is the Zhilong 3x3 M Mini and the ZhiChuang 5x5 M Mini.