Right of Cancellation
according to §356 Paragraph 1, sentence 2, No. 1, Civil Code (German Law):

You can revoke your contract explanation within one month without information of reasons in text form (e.g., letter, fax, email) or by return of the thing. The term begins at the earliest with preservation of this instruction. For the protection of the cancellation term the timely sending of the cancellation or the thing is enough. In case of an effective cancellation are the achievements received on both sides zurückzugewähren. If you cannot return us the received consignment complete or partly or only in worse state, you have to perform substitute in value of the goods received from us if necessary. With the surrender of goods this does not count if the deterioration of the goods is to be led back exclusively on their check - as it would have been possible to you possibly in the retail shop. For the rest, you can avoid the value obligation to indemnify, while you do not take the good like an owner in use and omit from everything what impairs their value. You have to carry the costs of the return on a return from a goods delivery whose order value amounts all together up to 40.00 euros if the delivered product goods correspond to the ordered ones. Otherwise the return is free for you.