Alpenflow Brandstoftransferapparaat

Combined four half-empty canisters into one before my last trip and didn't spill a drop, which honestly surprised me. The little thing lives in my pack pocket now and I forget it's even there. Wish I'd had this years ago instead of leaving fuel behind at every resupply.

Weighs almost nothing, so I actually forgot it was clipped in my pack until I needed it. Merged three half-empty fuel canisters into one before a trip and didn't spill a drop. Saves space and hassle.

Total lifesaver on my last backpacking trip — pouring the dregs from three canisters into one took maybe a minute, and it weighs basically nothing in my pack. The swap-and-share thing is what sold me, since my buddy and I kept trading fuel depending on who ran out first.