Mason Needle Holder Straight (266.7mm) (10.5inch)A Mason Needle Holder Straight Box Joint is a surgical instrument used to hold and manipulate suturing needles during stitching and suturing procedures. It is typically made of stainless steel and features a straight box joint, which allows for a secure grip on the needle. The 266. 7mm length is the size of the instrument and is used to determine the size of the needle it can hold.