Ballast Core: 1) BTA-39: 39mm width 2) BTA-41: 41mm width 3) BTA ... Can make according to clients requirement. Ballast Core:1) BTA-39: 39mm width2) BTA-41: 41mm width 3) BTA-42: ... 42mm width 4) Materials (silicon steel sheet): a) Bao steel: B50A1000, B50A800, ... An steel: 50AW1300, 50AW1000, 50AW800, 50AW600, 50AW470. Ballast Core(39/41/42 mm width)/ silicon steel part