The Starrett Lock Bolt Assembly is a top-tier replacement part designed for use with 6" square heads in Starrett combination squares. This durable lock bolt is crafted from premium steel, ensuring robust performance and longevity. The smooth black finish reduces friction, providing a secure and reliable lock for your measurement tools. Compatible with a wide range of Starrett models, this assembly is perfect for replacing lost or damaged bolts, maintaining the accuracy and functionality of your tools.