One of the biggest problems with wine and fruit cider is the thick layer of floating pulp. This makes tasting, sampling, and clarity experiments difficult. The wine thief is ideal for those who want to make professional measurements and adjustments to their fresh ferments without risking oxidation or contamination of the batch.
Just dip the long glass tube to below the floating pulp level. Use the bulk/finger to draw the required sample. The graduated scale helps in adding a measured quantity of fining agents, solutions, and reagents to your batch. So this thief serves two purposes and is a must to have for winery and professional brewers.