Complex sentence: Toughskins had reinforced knees for longer wear; came in slim and regular sizes; and were a blend of Dacron Type 59 polyester, DuPont 420 nylon, and cotton.
Split into simpler sentences: Toughskins had reinforced knees for longer wear and came in slim and regular sizes. Toughskins were a blend of Dacron Type 59 polyester, DuPont 420 nylon, and cotton.