There is a tiny tube shape container with magnetic power. You may easy find it in the small street park between two MTR stations of Line 2.
原来的第一版宝，没有磁性，全靠摩擦力固定，现在增加了磁性，因此任然要取放小心，注意不要被麻瓜发现。
The new version was upgraded after 2018. Thanks for Stacy and Sean. Move it from physical training zone to intelligence training place. 20190701