This is a solid sterling silver coin weighing 10 grams.
The Half-Shekel is a Torah Commandment first introduced by Moses in 1289 B.C.E. Every year at the time of Purim every Jew would bring a half shekel as an offering to the Temple in preparation for the busy Pesah period.
The rich cannot give more, nor the poor less. Whether that speaks of material wealth or ritual observance, all are equal in the fulfilment of this Commandment. Everyone has to fulfil this Commandment with exactly the same amount, you can not do it better than the next person, only the same, equally.
The Half-Shekel comes to remind the unaffiliated that they are at least half a shekel, and it comes to remind the very observant that they are only half a shekel. When you internalize this precept in the deepest reaches of your soul, it will change your personality. When you see yourself as half a shekel, mamash, then you will start to see every other Jew as also half a shekel. Even if there is a Jew that you hate in your heart, G-d forbid, when you see yourself as only half a shekel, you will see that the other person is also at least half a shekel, and you can no longer really hate them, because we are all equal, and one can not hate someone who is equal. Only when people think themselves a whole shekel, where no one else is worth a prutah (an ancient penny) can disunity and hatred exist. When you give the Half-Shekel you are saying, "I am also Half a Shekel, count me amongst the House of Israel!"
By giving your Half-Shekel you also establish a personal participatory relationship with Jerusalem and the Temple.