Sandberg String Hold-down for 4-String Righthand E-Bass
The Sandberg Stringretainer was especially developed for string guiding of classic Sandberg California, Panther, Electra and Forty Eight models and guarantees smooth tunings, safe tuning stability and the optimal contact pressure of all strings on the saddle.
Overview:
String Hold-down for 4-String Bass
Suitable for Sandberg California, Electra, Panther, Forty Eight
Gotoh Bass Bridge 201-B4 Chrome 
Fender HiMass 4-String Bass Bridge (Brass Saddles)
Sandberg String Retainer 4, chrome