Comparison : Item # 416-0614, 6" (152 mm) Aluminum heat tube with 1-1/4" NPT SS process connection
Item # 416-0616, 6" (152 mm) Aluminum heat tube with 1-1/2" NPT SS process connection
Item # 416-0613, 6" (152 mm) Stainless steel heat tube with 1-1/4" NPT SS process connection
Item # 416-0617, 6" (152 mm) Stainless steel heat tube with 1-1/2" NPT SS process connection
Item # 416-0515, 8" (203 mm) Aluminum heat tube with 1-1/4" NPT SS process connection