There are two different rums with the name "Jack Iron". One is "made" by Westerhall in Grenada and is a dark rum, 70% alcohol/volume. The other one is "made" in Carriacou and is even stronger and colourless. I have put the word "made" in inverted commas because in both cases the rum is distilled in Trinidad.
While Westerhall's "Jack Iron" is bottled in Grenada and is widely available in shops, I have never seen the Carriacou version in bottles. I did - however - see a lady at this year's Notting Hill Carnival wearing a "Jack Iron" T-shirt with a picture of a skeleton waving his arms around.
I was in Carriacou several years ago and ordered some Jack Iron in a bar in Hillsborough. Unfortunately I was distracted by something at the vital moment and failed to see what the rum was poured out of, but the rum was colourless and very strong.
Anyway, which of these two Jack Irons is the Rum of the Month?