(a) either to have the supplies brought into conformity, free of charge, by repair or replacement;  (b) or to have an appropriate reduction made in the price.  Any repair or replacement must be completed within a reasonable time and without any significant  inconvenience to the contracting authority, taking account of the nature of the supplies and the purpose for  which they are required by the contracting authority.  The term ‘free of charge’ in paragraph (a) refers to the costs incurred to bring the supplies into conformity,  particularly the cost of postage, labour and materials.  II.4.1.13 Assembly  If required by the tender specifications, the contractor must assemble the supplies delivered within a period  of one month unless otherwise specified in the special conditions.  Any lack of conformity resulting from incorrect installation of the supplies must be deemed to be equivalent to  lack of conformity of the supplies if installation forms part of the FWC and the supplies were installed by the  contractor or under its responsibility. This applies equally if the product was to be installed by the contracting  authority and was incorrectly installed due to a shortcoming in the installation instructions.  If required by the tender specifications, services to supplies must be provided accordingly.  II.4.1.14 Services provided to supplies  II.4.1.15 General provisions concerning supplies  (a) Packaging  The supplies must be packaged in strong boxes or crates or in any other way that ensures that the contents  remain intact and prevents damage or deterioration. Packaging, pallets, etc., including contents, must not  weigh more than 500 kg.  Unless otherwise specified in the special conditions or in the tender specifications (Annex V), pallets must be  considered as one-way packaging and must not be returned. Each box must be clearly labelled with the  following information:  - name of the contracting authority and address for delivery;  - name of the contractor;  - description of contents;  - date of delivery;  - number and date of specific contract;  - EC code number of article.  (b) Guarantee  The supplies must be guaranteed against all defects in manufacture or materials for two years from the date  of delivery, unless provision is made for a longer period in the tender specifications.  The contractor must guarantee that any permits and licences required for manufacturing and selling the  supplies have been obtained.  The contractor must replace at its own expense, within a reasonable time limit to be determined by  agreement between the parties, any items which become damaged or defective in the course of normal use  during the guarantee period.  16 