I am adding a shower drain to a 4" iron underground line.
I looked at Fenco and their flexable wye adapter with clamps said not for underground.
They also supply a saddle adapter. The saddle adapter does not say anything about underground use.
I would like to go from the iron line to the shower with PVC.
What is the best way to accomplish this task

No-Hub Bands,(see image) are what we use to convert from cast iron to PVC.
They are rated for under ground installations and are ridged where a Fernco Coupling is not. Good luck tom