After a week in use Addendum: Upper leak in the area of the valve wedge and not mend. For the second time in a mat of this manufacturer that already - apparently not an isolated case, subsequent trigger, stay away !!!
I have now bought a mat by Therm-a-Rest, which is despite a thickness of just 5 cm more convenient, was hardly more expensive and keeps hoffentlcih as long as my other Therm-a-Rest is in use for over 20 years.