The ZN12-T-WP is made out of one piece of carbon fibre (CFK) and is consequently combined with stainless steel elements (rods and nuts). The electronic displacement-sensor (linear motion potentiometer) is a weather-proof but not sealed sensor which is powered with a stable 3-5 VDC power supply. The ZN12-T-WP is our most sold dendrometer and is applicable for tree stems >7 cm in diameter in most environments. Dendrometers with the WP sensors are not recommend for extremely wet conditions.