Here's how it works - select the basic size of instrument you see listed below. These are all 100% digital aids that have a computer chip as its amplifying circuit. These are not programmed by computer....adjustments are made through manual trimpot controls so you can do some fine tuning yourself. Order the specific features that are important to you. If you have any questions about them , please give us a call. What you wind up with is a custom built digital aid made according to your specifications. Naturally the power and frequency response of the build-your-own aids is matched to your individual hearing loss. Here's how to have it your way.