Materials and workmanship to conform to description. All materials and workmanship shall so far as procurable be of the respective kinds described in the list of materials, Schedule of Quantities and/or specifications and in accordance with the contract and the Contractor shall furnish to the Employer with all invoices, accounts, receipts and other vouchers to prove that the materials comply therewith. The Contractor shall at his own cost arrange for samples of the material for approval and /or carry out any test of any materials.