These are couplings with different shaft centers that use the crank motion of a link. Power input at one end disc is transmitted via a link and center disc to another end disc.The amount of eccentricity is determined by the length of the link. Power can be transmitted smoothly when shaft centers are different. And since power is transmitted by the crank motion of the link, translation of shaft centers during rotation is possible. The standard NSS model has 3 x 2 links, while quasi-standard NSS models increase the number of links and the rated torque.