Arks lip blok prevents individuals from biting the straw and/or inserting the straw too far into the mouth. Use these mouthpieces to discourage tongue-thrusting, to promote tongue retraction, and to correct overall tongue position. They can also be helpful with tensing for controlled lip and tongue movement. The lip blok fits into most regular straws and comes in three different lengths - 1/4", 1/2", and the standard 3/4". They are also available in a flexible material (firm and soft) that allows you to cut them to any desired length. This kit includes one of each lip bloktm (the three sizes plus the two flexible versions). The goal is to start with the longest 3/4" and slowly progress to the shorter lengths in time. Cups and straws sold separately. Made in the usa out of medical grade, fda compliant materials that contain no lead, phthalates, pvc, bpa, or latex. Caution: use of these products should be supervised at all times.