The Massachusetts Department of Environmental Protection (MassDEP) is soliciting Bidders for a "Rolling Enrollment" Contract designed to establish and maintain a large pool of pre-qualified Contractors and Vendors from which the Departments throughout the Commonwealth can select for Ambient Air Quality Instrumentation, Parts, Supplies, Maintenance Agreements and Repair. The Contract will be available for use by Executive Agencies of the Commonwealth as well as other eligible entities listed on the Issuer tab on Comm-PASS. Each Commonwealth Agency and eligible entity is responsible for executing its own contracts and/or purchase orders and paying its own invoices for goods and/or services acquired from this Contract. Contractors will be responsible for marketing their goods and/or services to Commonwealth Agencies and other eligible entities.