The first thing you will notice about these strings is that they go right into tune and lock in. Players say they are “so stable it is almost eerie.” Now you can stand and deliver in tune notes at lower pitch that are clean and clear. Expect more and get more. Change tunings and be surprised how DDT's lock right in. Be surprised how little adjustments you make. DDTs deliver far more than just heavy gauges. Drop with confidence, drop with accuracy. DDTs maintain their intonation at lower tunings far better than any other string we have ever played or heard. Designed over a two year build and test period. Accurate Core Technology™ (ACT™) was developed to reinforce the core wire and fill in imperfections along its entire length. Superior core wire is recognized as the foundation for rich tone, accuracy of intonation and durability. Material: Stainless Steel. Hexagonal Core Wire reinforced with Accurate Core Technology™ with Ball End. Gauges: 55, 75, 85, 115, 135.