M Unit Purchases

We have had good success recently selling the large M units designed for cast iron 4 inch pipe vents. These will not be found on any modern homes, rather homes built prior to 1950. PVC hadn’t been invented, and cast iron pipe was the cheapest pipe around and 4 inch was really common. So if you got an old home with a lead flashing sealed vent check before ordering to make sure its not a cast iron 4 inch diameter pipe.