We have a little less than 2 bar to very high water pressure, but so far it was enough for each sprinkler. Here you will find neither in the article description still on the guide or package an indication that minimum water pressure must be present.
Etvl. would the manufacturer should build his hat a little easier and then can to put something to complain for the buyer.
Bottom line: If it works definitely a fun toy for hot days, but not for each water pressure.