The DaYan core is used in all DaYan 3x3 products, making it perfect for anyone who needs a replacement. The bigger 57/55mm version is used in the DaYan TaiYan, GuHong V 1, GuHong V2, LingYun V1, LingYun V2, LunHui, ZhanChi 57mm, ZhanChi 55mm. The smaller 50/42mm version is used in the DaYan ZhanChi 50mm, ZhanChi 42mm.
