求翻译：产品发运到合同签订的目的地，用户收货以后，由于工程设计的原因而引起的产品需要变更，我公司同意更换产品（但需在18个月内），但用户应承担变更产品而引起的费用。是什么意思？

Products shipped to the destination of the contract, the user receiving, because of the engineering design of the product of causes need to change, the company agreed to replace the product (subject to 18 months), but users should bear the changes caused by the product costs.

Products delivered to the destination contract is signed after receipt of the goods, as a result, users of the design caused changes in the products that require replacement of products (but my company agreed to in the next 18 months), but users should bear the costs arising from products change.

After the product ships out to the contract sign destination, the user receives goods, as a result of the engineering design reason causes the product to need to change, our company agreed (but replaces the product to have in 18 months), but the user should bear the expense which the change product

Products shipped to a destination contract, users after receipt, due to engineering reasons, products need to be changed, the company agreed to replace the product (provided in 18 months), but the user should bear the costs arising out of changes.