For NSF SBIR/STTR proposals, you will need two types of Letters of Support.
(1) Internal from all key personnel who are contributing and collaboration with you on the project, but are not W2 employees of your organization. These are typically consultants, subcontractors, and any other collaborators. You need letters from all such people.
(2) External from objective, 3rd party validators of your idea, commercial potential and technical capabilities. These are usually potential customers, key opinion leaders, investors, or other organizations with sufficient experience in your industry, who could speak to why your technology should be supported. You can include up to 3 such letters in your proposal.
Templates for these letters are available under the Letters of Support tab, within your NSF SBIR workflow. Editable versions are available by clicking on ‘Request’.
This is followed by options for sending the drafts by email from app itself or uploading a letter directly for easier management.