Carmex Internal Multiple Threading Insert holder - For Carbide External/Internal Threading Inserts - SR0063C21-5The Carmex Internal Multiple Threading Insert Holder is a precision tool designed for CNC mills to efficiently machine internal threads using indexable carbide inserts. Ideal for shops seeking reliable, cost effective internal thread milling with quick insert replacement. Internal threading holder: Mill Thread tool holder engineered for internal applications and internal thread milling on CNC milling machines. Multi insert capacity: Accepts 48 inserts