Review: Adjustable Spring Base Mounting Zinc

I had intended to use this spring base as a means of attaching my sand flag to the bull bar instead of the u-bolt clamp fitting that I already had. However, it does not appear as though I can fit it to my Toyota Prado alloy (genuine Toyota) bar. The base of the fitting is slightly larger than the mounting plate on the bar, but apart from that, when you read the fitting instructions, it says that this kit is not recommended for attachment to alloy bars, unless another type of fitting/adaptor is purchased separately. Of course, you are not aware of this restriction until after you have purchased the product and thereby get the opportunity to read the fitting instructions.
The product itself seems well made and very strong, so I have no issue with the quality, only the lack of clear and vital information prior to purchase.