For sale is 1 of a Valenite 4" Facemill # MM 040 6R 125 F with 6 (look to be perfectly new) Inserts. This is a high shear(positive rake) cutter so it is great for Alum , plastics and soft materials. The arbor hole is about 1.25" , the key width is about .512".It comes with all pictured, the 2 wrenches, grease and mounting screw. The mounting screw does not look like the original one, so you may want to buy one, or if it is the same size threads as what is on your arbor, then you may want to put a washer underneath if you think it needs it(as the head dia looks small for the counterbore size on the facemill.)
The dimensions over the 90 degree inserts are about 4.265" all the way across the inserts; about 3.67 to the center of the bottom of the inserts(so it will cut a flat path about to 3.67" across.
This is a excellent cutter, made in the USA, NOT made elsewhere for Valenite. This cutter also has the interchangeable insert pockets just in case the insert seats get damaged, then you only have to replace the seats and not the entire holder. This cutter may take the SPEW 43 style inserts.
Thanks for looking.