The olden style of spin strings achieve it by having textures on the strings (even naturally gut due to the internal spiralling). The new style is the smooth poly that slides during contact with the ball and then slides back. They both feel very different. I find that the olden style gets a more consistent result (but have to put up with some string position adjustment) and the newer style feels strange in that the result is not as consistent due to the slide factor changing over time. What do you people think of the 2 types and what do you prefer?