The new toolholder, for use with Seco's range of Snap-Tap thread turning inserts, features the Anti-Twist insert locking system to provide the most rigid insert holding possible. The Anti-Twist system has two significant design features. First is the use of a solid carbide pin located in the back of the insert pocket that resists distortion, common to standard toolholders, and prevents twisting and turning of the insert that can occur during machining. Secondly, the introduction of a new D-style clamp securely pulls the insert down and into the pocket. The result is increased toolholder life, less vibration, greater accuracy and performance of the insert, plus overall increase in threading productivity.