If you remember lock and use to be on all the time on QV with the guy who had a machine behind him which illustrated how many times you could lock and unlock the containers , He said you could use these containers thousand thousand of times.I bought a number of sets from QVC and some of the closing clips have broken off which make the container the un-useable, so may be they have had a number of complaints so they don't sell them as often. I complained but they put me onto a Chinese company and I never got the replacements.