Soundwave ships all Sontro OTC Hearing Aids with one size fits most receivers.If you determine that you need a longer or shorter receiver, by using the receiver measurement tool. The receiver measurement tool is located in your Sontro OTC Hearing Aid box, inside the clear cellophane envelope.  Please Contact Customer Support to exchange your receiver for free,  at support@hearsoundwave.com or 1-833-367-HEAR (4327).Soundwave Hearing Customer Support will create this exchange for free,  we do not require you to return the receiver that was shipped with your Sontro Hearing Aids.