Park Tool Threadless Nut Setter The TNS-15 is designed to install star-fangled nuts used specifically with 1  and 1.5 headset systems. The TNS-15 helps keep the nut straight and sets it to a depth of 15mm. To use, simply thread the nut onto the TNS-15 and tap into the forks steerer tube with a hammer (just like our popular TNS-1).