Polaroid Hi-Power flash cubes

[ped]

Just taken delivery of a beautiful Polaroid 440. It has the flash unit and a flash cube. Are these cubes disposable (i.e 4 shots then you bin it).. and if so, can anyone recommend a good UK source? My internet at home isn't installed yet (just moved house) and the net at work is very restrictive!!

Found these so far: https://www.interlight.biz/light-bulb/FLASHCUBE-HI-POWER&ID=FROOGLE-UK

Cheers
ped