Is it permissible to purchase building materials by paying the price in advance and receiving them later without seeing them at the time of agreement?

Scholars have differed regarding the ruling on purchasing an item without seeing it. The preponderant opinion is that it is permissible, provided the item is described in a manner that eliminates ambiguity, and that the buyer retains the option [of annulment]. If the item is found to match the description, the sale is confirmed; otherwise, the buyer has the right to annul the contract and reclaim the price. However, if the item is not present at the time of the contract, the contract falls under the category of salam (forward buying), which requires the capital to be handed over in the contracting session.