Measure the ID and the OD check the width it should be the same as the cross section. OD minus I.D ÷ by 2It has some hard plastic sealer wrings, kinda like piston rings. Harbor Freight does not show that it stocks parts for this model, but I have the parts book. I guess I need to call them just in case. It’s probably a copy of somebody’s name brand..
...but it will only do 21 degree full head 3 1/2 inch...