Bathroom shoe racker

The dimensions $26\times 7.7\times 4$ (most likely in centimeters) strongly suggest a shoe space saver or shoe stacker, which is a single-piece plastic or metal organizer designed to hold one shoe on the bottom and a second shoe on top, effectively stacking a pair vertically into the space of one. Given the extreme narrowness ($7.7$ cm or about $3$ inches is the width) and low minimum height ($4$ cm or about $1.5$ inches is the collapsed height), it is almost certainly a tool to maximize shoe storage in a tight space like a shelf or cabinet. You would purchase these in a set, and they would be used to organize items like sneakers, flats, or dress shoes, though they are usually too small for boots.