JMY210(Soft ferrite): When the antenna of the reader is in the environment of much more metal materials, to install the board of ferrite at the back of antenna, so that lowering the effect of metal materials for the performance and stability of the reader when reading card. It is easy to cut for soft ferrite. But the performance of soft ferrite is worse than hard ferrite. We recommend 1.7mm. The size can be cut freely and the frequency range is wide.