1of1 Custom's PRO-Fit Audio Cable will turn any PRO-Series ear plug into audio capable earpiece. 

The PRO-Fit is one of the smallest, lightest in-ear monitors available, right out of the box. The PRO-Fit cables are ideal for someone needing a basic level of sound quality or a convenient conversion to a custom listening device. The sound quality would be ideal for someone needing to hear a click track, wanting audio for exercising or other non professional use cases.  

*Available for purchase without molds or as a bundle with custom ear plug molds.
** Pro-Series filters sold separately