Thank you for viewing. I bought this a while ago, but I've only used it about three times. It has some wrinkles, but it's in good condition. It opens when you press the button. The button area is a little dull. When folding it, push it in all the way until it clicks, and you're done. Diameter: approximately 80 cm. When folded: approximately 20 cm. Famous maker, but I've forgotten which one.