The flame thrower portable No2, was nicknamed the "Lifebuoy" due to the shape of it's fuel tank. Also known as the "Ack Pack" it was of British design and used by infantry in the Second World war. However it was a very close copy of the German Wechselapparat design from 1917.

Over 7000 were produced between 1943 and '44. They saw service in Operation Overlord. 

The flame thrower consisted of a ruck sack style harness attached to a doughnut shaped fuel tank, (4 gallon/28lt capacity), with a spherical container holding nitrogen gas, used as a propellant. This enabled to weapon to have a range of around 120ft or 36m. At 29kg or 64lb in weight it was considered very heavy to carry. Although tested for transportation via a leg bag, it was eventually  transported by glider, due to it's weight.

In some versions a cartridge of cordite igniter was used. This was fitted in the nozzle in a 10 chambered cylinder. This gave the operator 10, 1 second bursts. This ignition system gave the operator the option to spray plenty of fuel over the target before ignition. 

In the film "A Bridge Too Far" the character portrayed but Alun Armstrong uses an "Ack Pack" in an attempt to destroy a pill box on the Arnhem Bridge.