You can use the substitution grip to replace compatible parts in 3D models.
A compatible part has the same size and type. For example, you can substitute a gate valve with a ball valve.
For fittings like reducing fittings, you may need to change the main size and reducing size separately, or replace a two-port fitting with a three-port fitting. The extended substitution menu options simplify the process of substituting reducing fittings in 3D models.