The Moisture Vapor Transmission Rate (MVTR) of eVENT Fabric?

Here's what Montane has to say (you'll note that the differences in face fabric have a lot to do with the ratings):

eVent® Super Lightweight Grid

* 86g/m² super lightweight 15 denier Nylon rip-stop
* Waterproof to a minimum of 30,000mm hydrostatic head with a minimum MVTR of 21,000g/m²/24hrs
* Laminated to oleophobic, air permeable hydrophobic ePTFE and Nylon Tricot

eVent® Lightweight 3 Layer

* 131g/m² 40 denier x 90 denier Nylon 6 (cotton touch)
* Waterproof to a minimum of 30,000mm hydrostatic head with a minimum MVTR of 22,000g/m²/24hrs
* Laminated to oleophobic, air permeable hydrophobic ePTFE and Nylon Tricot

eVent® Hurricane 3 Layer

* 118g/m² 40 denier Nylon rip-stop
* Waterproof to a minimum of 30,000mm hydrostatic head with a minimum MVTR of 15,000g/m²/24hrs
* Laminated to oleophobic, air permeable hydrophobic ePTFE and Nylon Tricot

eVent® Lightweight Abrasion 3 Layer

* 168g/m² 70 denier x 140 denier Nylon 6.6 plain weave
* Waterproof to a minimum of 30,000mm hydroststic head with a minimum MVTR of 12,000g/m²/24hrs
* Laminated to oleophobic, air permeable hydrophobic ePTFE and Nylon Tricot

Patagonia has a write-up about the travails of MVTR testing here:

http://www.thecleanestline.com/2008/07/from-the-pct-to.html

Even more complete discussion in a thread here several years ago about the interplay of vapor transmission and air permability called percent of naked

–mark

Thanks Guys