The main one was the Mk - 54 , a cylinder 40 by 60 centimetes and weighed 68 kilograms , fired by a mechanical timer it had a variable yield from 10 tons up to one kiloton .
The main one was the Mk - 54 , a cylinder 40 by 60 centimetes that weighed 68 kilograms . 
 It was fired by a mechanical timer and had a variable yield from 10 tons up to one kiloton .