Microsurgical Curved Castro Needle Holder, Diamond Dusted, 18 cm (7") Microsurgical Curved Castro Needle Holder, Diamond Dusted, 18 cm (7") Sign in to save to your list NHDCPVN Fine-tipped Microsurgical Needle Holders are used to grasp and guide the needle when suturing. Recommended suture sizes: 4-0, 5-0, 6-0. Where to Buy Ask a specialist