在聚苯乙烯的箱子里必须有一个大格子.里面的磁体必须由不可弯曲的塑料材料分开(塑料材料不能是硅树脂做的).

• The polystyrene housing must have one big cell . The magnets inside have to be separated each other by non-flexible plastic separators (NOT made of silicone!).