This is a great product, all the people who know how to use this product that have reviewed it have got it spot on! The negative reviews (1 star) are simply people not knowing how to use the product correctly. When the bottle arrives there is maybe a teaspoon of iodine crystals in the glass container, THIS IS NORMAL. If the water temperature indicator doesn't show the green dot to indicate how many capfulls of water to add, then the water is probably warm enough that it only needs one capful of the solution. Most of us will fill it up at the kitchen sink first, my tap water was pretty warm. Other possibility is the water is too cold, you'll be able to figure it out with your finger. I've used this product in the field and it has worked well. I usually add a bit more than needed (according to the chart) because I feel safer, and because I have spilled many times trying to dump a capful into a standard water bottle. Awesome product simply because If cost to amount of water you can purify, combined with shelf life. If I have a bottle of iodine tabs and open it up and use 6 on a trip, 3 months later the jar is bad and a total waste. A jar of tabs cleans 5 gal maybe, this product 500.

I thought it would be a smaller bottle, but it is almost the size of 2 golf balls stacked on top of each other. It is a glass bottle and might weigh around 4 ounces.

The label says there is 0.25 oz of iodine crystals in the bottom. Might be right. the bottle neck has a plastic tube insert that keeps the crystals in the bottle. the instructions say to keep the bottle full of water at all times so the iodine does not evaporate. There is a small thermometer indicator thing as part of the label on the bottle that is supposed to show a green dot next to the number of capfuls per liter to produce a 4 ppm iodine solution. I don't see a green dot on mine. Lacking this, I suppose you have to guess how many capfuls of solution to add per liter. The scale goes from 1.2 to 4 capfuls per liter.

I guess it is a good thing to have in a kit as long as you are OK with it's size and weight.

THe instructions say that the shelf life is very long, which is why I chose this product. I am not sure if I got a defective bottle, but I filled it with water as instructed and waited for the indicator dot to appear to let me know the dilusion level for adding it to water. The indicator strip on the bottle never changed. I waited a week before sending it back. I may have gotten a defective bottle, but am now looking into the iodine tablets instead.

Iodine is VERY concentrated. There is only supposed to be a little in the bottle. The space is needed for the water to create enough saturated solution to treat 1L of water. This stuff is great as it can handle heat and freezing and lasts forever.

Like several other reviewers, I ended up with a near-empty bottle that was essentially useless for the purpose of disinfecting water. An expensive lesson indeed! I can far more highly recommend standard iodine tablets - there are several manufacturers - and I can only warn potential customers to forget all about Polar Pure.