I got a Tech7, 26 L top box off ebay for £30. It is big enough to fit a full sized flip front helmet lying on its side. The base plate screws onto the YBR's luggage rack using the universal fitting kit. The box then fits onto that with a screw from inside the box. It opens with a key and closes without, so watch you don't leave the keys inside the box or you could lock yourself out. I got it to fit very securely, it has proved to be leak proof and has survived being frozen solid, a small crash and packed full on long journeys. However, one of the pins that keeps the hing in place came out. I replaced it with a screw that was long and thin and that will not be coming out. http://farm6.static.flickr.com/5054/5537381821_db46cfd146.jpg http://farm6.static.flickr.com/5253/5537382511_47e376ed7b.jpg