"Totally leakproof."
Whatever the claims of the many lockable food containers on the market, these Lakeland ones are the first I have used that have not let one drop of liquid escape. I use them every day for vinaigrette and cannot fault them so far.Just to be on the safe side, I have always washed these ones by hand as I don't know whether it was being dishwashed that caused the seals on my others to be compromised.