What is the amount of Zakat al-Fitr, is it permissible to give it after the Eid prayer, and is it permissible to give it in cash?

The Messenger of Allah, peace and blessings be upon him, obligated Zakat al-Fitr as one sa' of dates or barley, to be paid before the Eid prayer. The Companions used to give it as one sa' of food (wheat or other staple food of the people of the land), which is four handfuls with both hands filled, and is approximately 3 kilograms. The time for its disbursement begins from the night of the twenty-eighth, and its last time is the Eid prayer. It is not permissible to give its value in cash.