It can be confusing to determine if a component or a particular feature is considered an integral part of an orthosis or if you can ask for separate payment. Obviously, the best way to determine that is to follow the specific payer's guidelines. The problem is that many payers don't have really good guidelines or policies which make it easy to find that information so sometimes it comes down to trial and error.
The following tables come from Medicare LCD L33318 and include helpful coverage information about add on components for certain DME.
Table heading explanations:
Base Code: this refers to the main orthosis.
Add on (Payable): this column refers to other components/features which may be added to the base component which may be considered to be separately payable. However, that is not a guarantee of payment. Other rules such as determination of medical necessity also play a role.
Add on (not Payable): this is a non-exclusive list of components or features that may be incorporated into the base orthosis, but are not separately payable.