This is an adjuster that allows you to continue wearing your usual pants and trousers even as your belly grows. Attach the left and right buckles to the belt loops with snap buttons, and adjust the length with the slider in the center. By wearing the included sash (belly band) over it, you can conceal the adjuster and also keep your belly warm. I used the belt with my work uniform until I went on maternity leave, and I don't think the elastic part has stretched. The length is about 18cm when the slider is at its shortest, and about 22.5cm when it's at its longest (it can extend to about 35cm). The sash is in good condition as I haven't used it much!