Barb Adapter 3/4" Barb x 1/2" Spigot , The Glue Side glues inside a 1/2" Fitting which would measure 3/4" and a 3/4" ID tube would be glued over the barb.
This part is a Double 3/4" Barb Adapter x 1" Street.
The Glue Side glues inside a 1" Fitting (like a coupler) and the other side would accept (2) 3/4" vinyl tubing that would measure...
This part is a 3/4" Barb Adapter x 3/4" Slip / 1" Street.
The Glue Side glues inside a 1" Fitting (like a coupler) and the inside would accept a 3/4" Pipe flex or hard that would measure...
This part is an Air Manifold , Transition Type, 1" Spigot X (8) 3/8" Slip Barb..
You can use this with this Barb for a 3/4" Tubing connection to this Manifold: 3/4" Smooth Barb Adapter...