Mo. Rev. Stat. § 407.953

A manufacturer who sells an assistive device to a consumer, either directly or through an assistive device dealer, shall furnish the consumer with an express warranty for the assistive device. The duration of the express warranty shall be not less than one year after first delivery of the assistive device to the consumer. In the absence of an express warranty from the manufacturer, the manufacturer shall be deemed to have expressly warranted to the consumer of an assistive device that, for a period of one year from the date of first delivery to the consumer, the assistive device will be free from any condition or defect which substantially impairs the value of the assistive device to the consumer.