Hi! This sounds like it’s potentially a sleeve bushing/bearing. You should always dimension to its function. In this case, the OD is important because I’m sure it’s going into something. The ID is also important because there is likely a rod or shaft location. The hole for the rod and the outer diameter for the fit are independent, and need independent dimensions. Dimensioning the wall thickness may not convey the design intent to the manufacturer. Things that may be important other than the diameters are concentricity GD&T callouts.