The fabric has interfacing applied, giving it a sturdy construction. Depending on the size of the lunch box or containers you put in it, it can hold 1-2. If you also want to put in a PET bottle, I think it will only hold one. Size: Exterior: 20cm (height) x 29cm (width) x 10cm (depth) Interior: Thermal insulation sheet (15cm), inner fabric (5cm) As this is handmade, the finished size may vary. Also, while I make them carefully, there may be some distortion or minor imperfections.