Comparison : Item # B3641-30116BA1W, Vented Union Coupling Elbow Nylon Liquid Level Gage, 1 1/2” Sight Opening, 1/8” Male NPT Mounting Thread
Item # B3641-30116BA2W, Vented Union Coupling Elbow Nylon Liquid Level Gage, 1 1/2” Sight Opening, 1/4” Male NPT Mounting Thread
Item # B3641-30116BA3W, Vented Union Coupling Elbow Nylon Liquid Level Gage, 1 1/2” Sight Opening, 3/8” Male NPT Mounting Thread
Item # B3641-30116BA4W, Vented Union Coupling Elbow Nylon Liquid Level Gage, 1 1/2” Sight Opening, 1/2” Male NPT Mounting Thread
Item # B3641-30216BA1W, Vented Union Coupling Elbow Nylon Liquid Level Gage, 2 1/2” Sight Opening, 1/8” Male NPT Mounting Thread