Fuel Friend 1.5 litre fuel can
These things are the business. Big enough to hold a decent amount of fuel (or oil, or Balsamic vinegar, Paco Rabanne, most liquids, really), but small enough to stash on a bike. Perfect for overlanding, greenlaning, chopper road tripping, street trackering, anything where your tank capacity is limiting your ambitions.
The clever thing is they're designed to strap to numerous places on a bike with a common or garden luggage strap. Genius! Made in Germany, where they know a thing or two about overlanding.