Thanks S_A_T_S,
It is the Shuriken cannon, used one from my bits box (I think it is from another Eldar kit) as I was planning on using the others for my old FW Wave Serpent...sadly I discovered later that the two in the kit are not the same. As I was magnetizing this one, the spare that came in without fitting properly was not an issue.
The long painting war continues...
CB