This is what I found after one technical defense training + one game session.
Court (doubles) Review of EXBOLT 63 (Astrox 88S, 30/ 33 Lbs):
Everybody knows that any sting strung in high tension could get a high pitch but I found EXBOLT63 ringing much longer with a sort of sharp ceramic effect to it whilst in the background a damper tone that for me would relate to the extra holding time I found in the string.
The serve felt controlled and I got a good dive on the shuttle. In the return and third shot the release time felt fast but smooth and due to the extra holding time, I felt that I could place the shuttle where I wanted and that the angle became steeper.
The repulsion is really amazing which meant for me that my sometimes quite short lifts became perfectly long and before I calibrated the extra push quite a few lifts were 0.5 m over the baseline.
The holding time is much better than expected and means for me that my drives felt more controlled and almost diving down on the opponent’s side. My choice of direction felt sharper and the placement of the shuttle more exact.
I had loads of control in shorter play to the net both straight and cross-court, like the shuttle died down really fast after the tape.
I felt really comfortable in my defense due to the extra repulsion I felt in EXBOLT 63. From any pressured position I could easily get away with a really good lift.
I was really afraid that I would loose some depth in my attack coming from AB Boost (30/33 Lbs with 15% pre-stretch) to EXBOLT63. But the added repulsion in combination with the surprisingly good holding time felt naturally sharper with a quick release but also with plenty of depth and control in full smashes. Stick smash was amazing, drop shots really fast and slicing the shuttle A-OK.
All in all, I would say that EXBOLT 63 for me is:
Significantly good repulsion, quick release with amazing holding time and really durable with little tension loss.