Add punctuation: Featuring proprietary circuit designs and meticulous tuning the Katana series combines traditional craftsmanship and breakthrough functions to produce true nextgeneration rock amplifiers
A: Featuring proprietary circuit designs and meticulous tuning, the Katana series combines traditional craftsmanship and breakthrough functions to produce true next-generation rock amplifiers.

Add punctuation: Detection of metal parts in nonmetal products
A: Detection of metal parts in non-metal products.

Add punctuation: He was a pertinacious controversialist but in any personal discussion his humorous twinkle was disarming
A:
He was a pertinacious controversialist, but in any personal discussion his humorous twinkle was disarming.