Every small part on a machine was chosen for a reason. Sometimes obvious, sometimes not. Substituting a "similar" part gambles that whoever designed it in was overspecifying — a bet that costs almost nothing to win and a service call to lose.
This is the genuine Nilfisk Advance OEM COUPLING 3.5IN OD 16 GA ZINC, part number CP35042B-16Z, brand new in the box. Factory spec, factory fit, ready to install.
Not sure this is the right part for your machine? Send us the model and serial and we'll confirm.