Zippo lighter fluid is great for filling:
When your windproof lighter is out of fluid, fill your windproof lighter with Zippo lighter fluid. Hold the lighter in one hand. Use the other hand to remove the insert. Fill slowly and never over fill. You can do this by lifting the felt pad to reveal the packing material in the fuel chamber. Saturate the packing with Zippo Lighter Fluid. Stop filling when fuel reaches top of the packing.
To fill your hand warmer with lighter fluid,pour Zippo Lighter Fluid into the appropriate 6 or 12 hour plastic filling cup provided in the package. Then carefully and slowly pour the contents of the filling cup in to the filling hole on the Hand Warmer body, while maintaining the Hand Warmer in an upright position.
Refill the fuel canister with Zippo premium lighter fluid when the canister is empty.