My X1 mill is gutless at low speeds , spotted this in tool shop less than twice the price of a HSS slitting saw , so I can run it at twice the speed I hope .
Picked up something similar a while ago, but 120mm dia. Thought that I could use it it cut fins on an square aluminium head and cylinder, but I am yet to try it out.
I have one it is 3 3/8 inch in diam. .045 thick and i have used it on steel
brass & alum..
Had to make a arbor because the center hole is MM.
It would be better if it had twice as many teeth but it does work well for me any way.
Have to be careful not to feed to fast.