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About us

Thermwell has been keeping America warm for more than 100 years.

Founded in 1910 as Thermwool, we introduced the globally renowned Frost King brand of weatherstripping in the 1960s and have continued to expand our brand and reach over the years to create a brand portfolio that includes:

Frost KIng thumb thru catalog
Frost KIng thumb thru catalog
  • Regent Tape, producer of world class masking tape.
  • Mortite, manufacturer of world famous Mortite Caulk.
  • Eagle Lamp Company, manufacturer of Eagle Hurricane Lamps and scented oil.
  • W.B. Marvin, maker of the world-famous W.B. Marvin Window Screens.
  • PortaSeal, maker of world-class door and garage insulation.
The Frost King snowman

Each acquisition has added to Thermwell's strength and dominance in the do-it-yourself market.

Manufactured at our factories in Mahwah, NJ, and around the country, Thermwell’s entire line of products is designed to empower homeowners and help them save money and energy.

Frost KIng thumb thru catalog
Frost KIng spring bronze weatherstrip
Thermwell’s Mission

Save Money, Save Energy

From the gutters on your roof to the AC unit in your backyard to the windows in your living room to the vents in your basement, Thermwell has the right product at the right price to save you money and energy.