In fetching purple
Magnetic, heavy duty, purple, expands to make it bigger, zips up to make it smaller again , has its shoulder strap, did I mention it's purple?, but I cut the 'rucksack' harness out as it intruded too much into the bag. I've used this on several bikes over the years, it seems to be just the right size for the cr@p I tote around. My new bike has a plastic tank and this just keeps slipping off!
£15 plus post or collect from the Carlisle area
Here it is on my old AT, a pretty good colour match too!