Go to http://www.nikwax.com/en-gb/webquiz/index.php and answer 4 questions correctly to and submit to receive a free bottle of Nikwax Tech Wash Travel Gel. If you don't know the answer to the question, you can click on clue or check answer to get the correct answer.
Rules: "You can repeat the quiz as many times as you like and you will get different questions each time. You can only win a maximum of one free product per household every 3 months. However, for every 3 friends you have referred that play the quiz, you will be able to play and win again immediately. No cash alternative available. Open to residents in US, Canada, UK, Germany, Switzerland, Austria, Denmark, Netherlands, Belgium and Luxembourg. Nikwax, or its representatives, reserves the right to substitute an equivalent prize should the prize stated be unavailable. "