28.4.1. Maintenance pricing shall include labor, transportation, and all back-up batteries. All system batteries shall be replaced on an annual basis. Each system shall be inspected and tested twice (2) yearly. These inspections shall include the cleaning and adjusting of all system components, 50% sensor activation, and communication to central station verification. Said tests and inspections shall be conducted on weekdays outside of normal business hours (5:01 PM – 7:59 AM) in order to minimize inconvenience to inhabitants or as specified in the Offer Sheet. 28.4.2. The Vendor shall promptly report all deficiencies to the Agency Contact Person. Request to repair and/or replace parts shall be approved in advance by the Agency Contact Person prior to any actual work being performed by the Vendor. Parts and materials shall be invoiced not to exceed 10% above Vendor’s cost. The State reserves the right to request the Vendor supply the State with invoices from suppliers documenting the Vendor’s cost. 28.4.3. Alarm monitoring services shall consist of twenty-four (24) hour monitoring and dispatching services from an Underwriters Laboratories (“UL”) approved central station. The central station shall have been in business for a minimum of five (5) years and shall have passed a minimum of two (2) consecutive UL inspections.