Sold individually, these heavy tension return springs are the correct size and tension for all Kahler bass and multi string guitar tremolos (2200/2300 Pro, 7200/7300 Hybrid, 4200/4300 X-Trem, 2330 Flyer and "Gibson" stamped models). Will also fit Accutune Type 1 tremolos.
Depending on your model, you may need between two and six springs. For six string CAM guitar tremolos you'll need only two springs, either a standard tension set or a heavy tension set, depending on the string set used. String sets containing strings sizes between .008 and .048 should use 8412 standard tension springs. If any string is larger than .048, you must advance to these heavy tension springs to compensate for the extra pull.
Fulcrum models such as the Kahler 2720 Spyder, 2710 Killer, 2760 Steeler, 2500/2520 Traditional, Floyd Rose and others should use 8414 Fulcrum Springs
All tremolo system springs should be changed every 3-5 years. Metal fatigue is the #1 reason for erratic tuning stability.
So you don't do the whammy thing anymore? Whammy Parts has a CAM locking clip that will turn your Kahler guitar or bass CAM tremolo into a fixed bridge. Chuck those springs, now you can drop tune with a simple twist with your fine tuners. See 8411 Locking Clip.