To use these boots, simply unzip the inside closure and slide your feet in. They're designed to stretch over your knees comfortably. When it comes to sizing, always refer to the US sizing guide and adjust if you're from Australia. As for maintenance, use a soft cloth to wipe off any dirt or dust. Avoid exposing them to extreme heat or moisture as this can damage the polyurethane material. Since this is a pre-order item, be patient while waiting for it to arrive. If there are any issues with the size availability, we'll get in touch with you promptly.