Already assembled in the box with an extension, the gate can be used anywhere and folds down quickly for easy storage. It does not require an exact measurement. Make sure the gate size is large enough so that the gate can be angled rather than placed straight across the opening. Having the gate angled greatly improves its stability. Suitable for puppies or other animals of the same size. Perfect for use in front of stairs, kitchens, balconies, bathrooms, bedrooms, entrances, hallways, etc.