... 30cm, 35cm, 40cm ApplicationIt is applied to investigate tress growth. Through drilling tree core samples, without destruction of trees ... .3 meters of the tree, horizontally spin the growth awl to the trunk center, when reach the center ... and get wood core within core extractor. Tree growth condition can be analysed by watching wood core color ... pipe length: 20cm, 25cm, 30cm, 35cm, 40cm Plant Growth Awl