Comparison : Item # B3565-21, 1/4” Male NPT Adapter for Steel Liquid Level Gages with 1/2"-20 Straight Thread
Item # B3565-22, 3/8” Male NPT Adapter for Steel Liquid Level Gages with 1/2"-20 Straight Thread
Item # B3565-23, 1/2” Male NPT Adapter for Steel Liquid Level Gages with 1/2"-20 Straight Thread
Item # B3565-24, 3/4” Male NPT Adapter for Steel Liquid Level Gages with 1/2"-20 Straight Thread