FAR 52.219-6
Notice of Total Small Business Set-Aside
What it says
Reserves the acquisition exclusively for small business concerns. Only offers from small businesses (under the size standard tied to the assigned NAICS code) will be considered for award.
Why it matters on DIBBS
The most common set-aside on DIBBS RFQs. If a solicitation carries this clause, large-business quotes are ineligible — competition drops sharply, which is exactly where small suppliers win.