Convert from shekel [Hebrew] to arroba [Portugal]

Unit Definition (shekel [Hebrew])
The shekel is an ancient Hebrew unit of weight (and also a coin having that weight). The shekel was the Hebrew version of a Babylonian unit used throughout the Middle East. Accounts differ on its size. A frequently quoted equivalent is 252 grains, which is equal to 0.5760 ounce (avoirdupois) or about 16.33 grams, but other sources quote a value of 8.4 grams or various values between these two extremes.

Unit Definition (arroba [Portugal])
The arroba [Portugal] is a traditional unit of weight in Spain and Portugal, equal to 1/4 quintal. However, the Spanish and Portuguese quintals are of different sizes. In Portugal and Brazil, the arroba traditionally equals 32.38 pounds (14.69 kilograms, but in recent years this has been "metrized" to be exactly 15 kilograms). The arroba has also been used as a metric unit equal to exactly 15 kilograms. The name of the unit comes from ar rub', Arabic for "the quarter."