Comparison : Item # 2015-8-8S, 2015 External Pipe/External Pipe (NPSM)
Item # 2015-12-12S, 2015 External Pipe/External Pipe (NPSM)
Item # 2015-16-16S, 2015 External Pipe/External Pipe (NPSM)
Item # 2015-24-24S, 2015 External Pipe/External Pipe (NPSM)