The D1 Dendrometer is a simple tool that allows you to manually measure changes in the circumference of tree stems over time. The D1 is designed to be installed, left in place and periodically visited to record changes in the circumference resulting from tree or stem growth.

The D1's measuring tape is made of low-friction, low thermal expansion Astralon plastic. It wraps around the trunk of a tree and fastens with a spring mechanism that allows the tape to expand as the tree grows. The researcher measures the change in diameter, typically at longer intervals (once a year). The measurement scale is in units of ? so there is no need to convert circumference to diameter. The D1 has a specially shaped frictionless Vernier scale to make it easier to take a precise reading. UMS has additionally reduced friction by manufacturing the eyelets without burrs and eliminating printing on the bark-side surface of the tape.

The D1 measures trees with diameters from 10 to 66 cm. Two tapes can be connected to measure larger trunks. Stems less than 40 cm in diameter should use the short spring and the longer spring should be used on stems > 40 cm in diameter.