Extech mo257 pinless moisture meter extech mo257 the extech mo257 pinless moisture meter is a non invasive instrument for monitoring moisture in wood and other building materials with virtually no surface damage it reads relative moisture from 0 0 to 100 0 with 0 1 resolution in wood particle board carpeting ceiling tiles and more using non invasive high frequency sensing technology the pinless measurement depth extends from 20mm 0 78in to 40mm 1 6in below the surface the meter fe