Featured Products

Thel-Mar is THE manufacturer of the Portable Compound Volumetric Weir.  We are a family-owned and operated business for over 40 years.  All of our products are made in Ohio. Thel-Mar distributes our weirs internationally.

The Thel-Mar Volumetric Weir is the industry's most accurate and affordable portable flow-measuring device. Our faceplates are laser engraved for longevity and have been proven to be the most accurate solution for highly variable, partially full pipe measurement.