Hi men! well.. SMDJ series to littelfuse say "RS232 Interface Protection with High Surge Requirement" and support 3000W!...
Bourns use SMBJ series and this type of TVS support 600W!
The selection depend to your application designd and requeriments.. if you aren´t high specifications, use SMBJ (it´s more cheap)
I hope I have helped you, greetings from Argentina