 The explosive was wrapped in a beryllium oxide channel filler, which was surrounded by a uranium radiation mirror.The mirror and channel filler were open ended, and in this open end a flat plate of tungsten propellant was placed.The whole unit was built into a can with a diameter no larger than and weighed just over so it could be handled by machinery scaled-up from a soft-drink vending machine; Coca-Cola was consulted on the design.