A variety of N-substituted derivatives are based upon the base chemicals ofthat provide for the induction of cavernosal relaxation in animals. The permission packet has information for a user device to access content through a connection of a content delivery network so that in response to the permission packet, a first connection from the content delivery network to the user device may be opened by the user device. Speakers are selected corresponding to the speaker models, the number of which is smaller than the predetermined number and the short-time speaker sore of which is high, from among the speakers having a high long-time speaker score. A pretensioning element is mounted in the casing of a first ring in frictional contact with the second ring in order to apply a resistant torque during the rotation of one ring relative to the other.