Revolutionary locking mechanism keeps tips secure! Easy to change, no tools are needed. Includes 8 different sizes of Addi Lace Tips, US 4-11 (3.5mm-8mm), five different lengths of extremely pliable blue cords (16"/41cm, 20"/51cm, 24"/61cm, 32"/81cm, and 40"/102cm), and one connector piece to store stitches or combine cords. Allows for both 16" (41cm) and 20" (51cm) applications.