The Beiter String-Tool is a Multi-Purpose-Tool for many different tasks, not just for working on your strings. They are sold in pairs because you can and should use them as a pair. With the Beiter String-Tool you can easily count the number of strands in your string and properly install your Peep-Sight. After you have pushed the first String-Tool through the string, you can count the single strands by inserting them into the grooves on the Tool. To be able to install the Peep-Sight easier, you can use the second Beiter String-Tool generating a bigger working window. The Beiter String-Tool is a Multi-Purpose-Tool for many different tasks, not just for working on your strings. It can also be used like a fingernail! Basically you can... Split a string for Peep-Sight installation Easily count the number of strands in your string Determine the middle of the string by counting the strands so ensuring that the Peep-Sight is in the center of your string You can start a serving extremely quickly and simply Serve a Beiter nocking point more easily, defining the correct starting position Use the String-Tool as a shaver to take off a rest or glue from your bow!