Ideal for multi-kid families or children who love to ride with friends, the Kettler tandem insert turns your single Kettler tricycle into a tricycle built for two (or three or four). The insert's modular build fits any S-frame Kettler trike, and is custom designed for expansion. In other words, you can buy two or three inserts and turn your child's trike into a stretch tricycle. The insert's innovative Quick-Adjust knob makes installation quick, easy, and secure, while the spacious high-impact resin bucket seat is comfortable and form fitting. As a final detail, each insert includes an extra pair of handlebars and footrests. The tandem insert is also backed by a three-year warranty.