I have used one of these for about 15 months and always carry it when I am out.
I have always used mine dry but wash it over about every 4 months or so in warm water, dry it and it is ready to use again, this is a fantastic little stone and it puts a razor sharp edge on all of my knives, I have used the diamond side for some really dull knives but mostly I use the ceramic side for just touching up.
10 out of 10 for this stone..
Have fun, shoot a stick.