123 Search provides powerful and flexible ways to search, explore and interact with model elements and data objects that exist in a model database.

 Here is a list of just some of the things you can do:  

• Schedule elements that are not available using Autodesk® Revit® schedules
• Versatile filter
• Explore and gather useful model data that are not exposed by Revit parameters or Dynamo
• Batch-edit elements in a table view, or using Excel spreadsheet
• Show preview images of family types
• Key schedule that allows shared parameters
• Spell check all textnotes, all dimensions with text override, and all other text values that are available in the model database
• Clean up model elements in legend views, as well as in other hidden places

123 Search Blog Post has a more complete documentation.