https://en.hamikdash.org.il/about/we-need-your-support/the-temple-coin/
The Half Shekel medal is from puter metal with at least 9.6 grams of halachically required pure silver
:Income from sale of the coin will be used for three major purposes
Building the Temple,
Practicing procedures for the sacrificial rituals,
Preparing spiritually, ritually and educationally for Temple Services