First of all, we are talking about a new and unique security thread found on both banknotes. This thread is fundamentally different from that used in old banknotes. It was also further modified from the version used on the 2,000 ruble note.

Thread includes three security features in one. The first is the volume effect that the repeating image of the ruble sign has, which is immediately visible when you look at the thread. The second sign is the “change effect”: when the viewing angle changes, the image on the thread completely changes. The banknote also includes two optically variable security elements. One of them was already visible both on the updated 100 ruble banknote and on the 200 and 2000 ruble notes. 

The element is located on the left side of the front of the banknote. When the banknote is tilted to a uniform area with the word “RUSSIA” written on it, multi-colored numbers of the “1000” or “5000” banknotes appear on the left side of the banknote, respectively. When a banknote is rotated 180 degrees, not only the colors of the digits change, but also the color scheme.

Source: Ria, as quoted by News Unrolled.