Immersion Water Heater Electric Camping Accessories - 120/240V - 300W - Dual Voltage Portable Water Heater Travel Accessories - Immersion Heater for Tea - White

Instructions say: 10 oz to boil 5-6 minutes @120V. Ya, that's about what it takes. About 1/4 that long @240V. So, this mean there is no voltage reduction (or transformer) in the adapter - its just straight pin to pin connection through the adapter. That means its getting a heckuva lot hotter (duh) @240V. If the resistance of the heating element stayed the same (using V sq./ R) it would consume 4x the wattage, but as we electronics people know, the resistance of the heating element increases with higher temp. so its not that much of an increase (I didn't measure the amps so I don't know exactly how much more wattage it consumes at the higher voltage). Bottom line - this thing would be very easy to overheat and burnout the heating element (which several people have done) using it at 240V, so do NOT have it plugged in unless its submerged in liquid first, and unplug (allowing a little cooling) before removing from your liquid. This is not as critical using @120V but it's still a good idea. This heater should last quite a while if you follow these precautions. Whew! I think I'll heat some water and have a cup'o java now.

This comes with a plug adapter for other countries. I used this in Namibia with the adapter. Super fast hot water using 230v. Very slightly slower in the US with 110v. Be sure you have somewhere safe to rest it while it cools.

Muy funcional xa los viajes. Tienes agua caliente en minutos xa preparar tu té favorito. Recomendado

Be sure to check dimensions before buyingIt is so large that to use it in a regular size cup is not practicalIt operates properly and heats water fast so only taking a star off for size

Hope this works as advertised! I tried it on 110 plug in the US, and it gets very hot. It melted an edge on a travel cup with a rubbery edge! With 220, it will get hotter even faster, so I will need to very careful. The hook that atttaches to the cup edge while water is heating does not hold the heating element away from the side like it should.