I travel domestically in China a lot. One time, I was told at check in I had to have a lock (out of probably 50 flight last year) other than that, I have never used one or had issues with baggage. I travel with one in my bag now to comply. Frequently, no one checks, so it is not a problem. Weight and number of bags is a separate issue. They really police the weight limit and charge you extra. I think they also limit you to one bag. Watch how you pack. Hotel laundries are good and cheap in China if you stay a few days in one place. I now travel light and wash once or twice while there.... China hotels are terrific values... Stay at nice one's you won't regret it...