ANSWER: The best and easiest is boiling hot water. It applies the heat evenly to the sleeve and is not hot enough to melt the sleeve. But you can use any heat source, a hair dryer, heat gun, stove top, even the dash of your car in the summer. You will need to be careful to not apply to much heat or the sleeve could melt.
ANSWER: Currently the colors are Red, Green, Blue and Yellow. Custom colors can be requested.
Answer: With most medium size key heads this is not a problem but with our small size sleeves we precut a moon shaped piece out of one end. If you have a medium or large key head where the sleeve covers the key ring hole you can cut a moon shape from one end.
ANSWER: Yes, but we recommend the Sharpie Industrial marker, it is the best we have found for writing on plastic.