It adopts a single card slot design, which effectively prevents the contacts from being scratched when it is carried around and rubbed against items such as keys and coins.
The inspiration comes from the design concept of a symmetrical double-chamber box.

(Added on March 15, 2017)
This product was launched in response to the strong demand from many creators.
The model is based on the original design drawn in ViaCAD and parametrically modeled in OpenSCAD. The default parameter settings strive to be as faithful to the original as possible and to restore the closest possible design details.