I have multiples available. Some are unused and others are issued, but all are in good and usable condition. All are marked with the size stated here, but actual size appears to vary a little. Dated from the 1970's to the 1980's. Unpacked weight is 0.22kg.
Airmail Worldwide (outside of Europe): US$16
Surface Mail Worldwide (outside of Europe): US$11
Airmail Europe (outside of the UK): US$11
1st Class Mail UK: £3.60