Designed to work universally with any arrow and any bow to determine where to place your string nock buckle. Simply insert your arrow in the String-T and then mount it to your bow string (note the "up" arrow on the String-T), while also setting the arrow nock on the string, as if ready to draw. Raise and lower until the arrow barely rests on the arrow rest. When you're happy with the position of the arrow, install the buckle on the string, where the string and the top of the arrow nock meet.

Done.