Complex sentence: Another early American packaging industry pioneer was the Kieckhefer Container Company, run by John W. Kieckhefer, which excelled in the use of fibre shipping containers, which especially included the paper milk carton.
Split into simpler sentences: Another early American packaging industry pioneer was the Kieckhefer Container Company, run by John W. Kieckhefer. This excelled in the use of fibre shipping containers, which especially included the paper milk carton.