Our Products Telephone Series (PR) Telephone Plug (PRB) Telephone Plug Cover Telephone Plug Cover Photo Series Product Name Download Product Info. PRB501 Telephone Plug (PRB) PRB502 Telephone Plug (PRB) PRB503 Telephone Plug (PRB) PRB504 Telephone Plug (PRB) PRB505 Telephone Plug (PRB) PRB506 Telephone Plug (PRB) PRB507 Telephone Plug (PRB) PRB508 Telephone Plug (PRB) PRB509 Telephone Plug (PRB) PRB510 Telephone Plug (PRB)