Is Ross W1616C2020 a valid part number, or is there a replacement?
Some years ago, "W" prefix called-out “World Thread” … Ross’s own sort-of universal thread. Supposedly it was compatible with both BSPP (European) -and- NPT (North American) fitting types. Today, only NPT threads are available. So customer may need to adapt if they were using Euro thread fittings.
Consider 1616C2020,-plus- an alpha suffix to indicate coil voltage (Z = 120 VAC, W=24 VDC, etc)