This grounding wire is required if using a wind speed or wind speed and direction sensor with the H21-USB or if the H21-USB will be placed in an exposed location on a tripod or tower.

To see the full specifications for this product, please see our product manual found under the PDF Manual for H21-USB

Dimensions: 22.2 cm (8.75”)

Weight: 5.3 g (0.19 oz)