Ill. Admin. Code tit. 44, § 1500.2050
b) Brand Name or Equal Specification
1) Brand name or equal specifications may be used when the Procurement Officer determines in writing that:
c) Brand Name Only Specification
d) Proven Products
The supply or service may be rejected if it has not been offered to other governmental or commercial accounts for at least one year. Specifications may require that the supply or services have been used in business or industry for a specified period of time to be considered.