This is hard to say. I have never seen a Selkirk weight finished this way (unpolished with a label - that combination is odd). Also, mini Selkirk weight are less common. On the whole, this weight does not look Selkirk to me; but I may well be wrong. All sort of unfinished/unmarked weights came on the market when Selkirk closed abruptly in 2006. So it could be one of those.
I am not sure that I am being very helpful here... Sorry.