This invention relates to a biaxially stretched product comprising a copolyamide comprising monomeric units of: aliphatic non-cyclic diamines X and aliphatic non-cyclic dicarboxylic acids Y or aliphatic non-cyclic α,ω-amino acids Z, and diamines M and diacids N in an amount between 0.1 to 2 wt % based on the total amount of copolyamide, and in which M and N are cyclic, and wherein the product has been stretched at a temperature of between the glass transition temperature (Tg) and the melting temperature (Tm). A method of preparation is claimed, as well as a multilayer film comprising the biaxially stretched product.