Badminton string tension by level — 17–22 lbs for beginners, 22–26 lbs for intermediates, 26–30 lbs for advanced — plus what BG65, BG80 and the Yonex BG-string family actually feel like in the hand. Covers the control-vs-sweet-spot trade-off, the manufacturer-max ceiling that protects the frame, the plastic-shuttle 2–3 lbs adjustment, and the honest answer to 'should I restring?' Most club players are 4 lbs over-tensioned.