User Manual for BACK BAY models including: 51 or higher, DUET 50 PRO Earbud, DUET 50 PRO, Earbud
New Duet50 PRO Manual Web
The number on my case is 51 or higher
Duet 50 Pro Earbud Instructions – Back Bay Brand
New Duet50 PRO Manual Web ?v=1730828641 Adobe PDF library 17.00 Adobe Illustrator(R) 24.0