Everyone who crosses over to those counted must pay a half shekel, according to the sanctuary shekel, which weighs twenty gerahs. This half shekel is an offering to the LORD.
Jewish Publication Society of America Version (JPS1917) - Exodus 30:13 >This they shall give, every one that passeth among them that are numbered, half a shekel after the shekel of the sanctuary — the shekel is twenty gerahs — half a shekel for an offering to the LORD.