In lieu of initially forwarding complete bid sets, the contracting officer may send presolicitation notices to concerns. The notice shall-

(a) Specify the final date for receipt of requests for a complete bid set;

(b) Briefly describe the requirement and furnish other essential information to enable concerns to determine whether they have an interest in the invitation; and

(c) Normally not include drawings, plans, and specifications. The return date of the notice must be sufficiently in advance of the mailing date of the invitation for bids to permit an accurate estimate of the number of bid sets required. Bid sets shall be sent to concerns that request them in response to the notice.