I have got 30 brand new and unused double ended RiRi zips.
The zips come in packs of 10, I ordered these from the UK RiRi agent when I was doing Otterwell . We used these for our anoraks and they are fantastic zips & do not come cheap.
Each one measures 29.5 cm and can be made shorter if necessary.
I know there are a few on here starting their own brands etc so thought it was worth a try.