There is a difference between limiting the scope of brand selection and designating a unique brand. For the latter, China's laws are strictly extinct.

Is the only authorization unique to the project or the bidder?

A better way is to recommend your desired brand to Party A. You can provide the information of the manufacturer and its application performance to Party A for evaluation, so that it can increase the brand by changing the bidding documents.

The letter can express the desire to increase bidding brands and adopt brand advantages (low price, good quality and high cost performance). ) in any form, and never mention the word fair and reasonable. This is obviously a search.