Looks ok but it doesn't say how many watts it is. I am also surprised that its 'submersible' Id never have that under water!
That only thing I would say it that you get what you pay for. The Arcadia arc lights are £28, that should tell you something, but I guess worse case you've got a cheap desk lamp!
i wouldn't submerse it either! i have seen an arcadia over tank luminaire 30w i might get that it is £80 though but like you say, you get what you pay for.