If you need a lock bolt assembly for your Starrett level, the PT99006 is an excellent choice. The high quality replacement part can be used with 12" square heads. It fits the Starrett brand and measures 2ZUR1, 3AEP9, 26Y957. The steel lock bolt assembly has a type of replacement and material of steel. With this PT99006 Lock Bolt Assembly from Starrett, you can get your work done efficiently and easily.